I've had the opportunity to speak in public on technical topics on a few occasions, and attended a lot more such talks. That allowed me to notice some positive and negative patterns. Some of them are not covered, or not properly emphasized, in various online articles giving tips on public speaking. Furthermore, I noticed that following to a tee the commonly-passed advice (slides, flow, attire, body language, attendance handling, tactical stuff that I consider marginal) still isn't enough hedge against cringeworthy talks. In the following I will attempt to distill the observations I have accumulated on both sides of the audio amplifier into a few tips that I hope you'll find useful.
Public speaking is a complex topic featuring books (most of which I haven't read) and classes taught by experts (none of which I've taken). Therefore, be warned that the lower bound of my advice's value is what you paid for it. However, I'm as much a bithead as you are so the material below is direct, to the point, and aimed straight at helping a fellow hacker in need. This is where the rubber hits the road.
The advice below applies only to longer talks (30 minutes or more). Short talks (10-20 minutes) and long talks are both challenging, but the challenges they present are very different. A short talk emphasizes tactics and asks for a well-rehearsed, tight delivery that moves along with smoothness and precision. Short talks are prevalent in academic circles and enjoy a rich and good-quality lore, to which I don't have much to add. Long talks are challenging in other ways because they emphasize strategy, improvisation, and adaptation. Let me point below a few key aspects that you should pay attention to when giving a long technical talk.
I can't stress enough how important this is: when embarking on preparing and giving a public talk it's essential to be animated by mainly one desire - to share something that you believe is interesting. In this context "interesting" means that you are convinced you have some unique insights that your audience can't easily acquire in reasonable time by e.g. reading an article.
To clarify the above, consider a counterexample. Most corporations have a new hire orientation process that includes some presentations (human resources, safety, technology, and so on) given by the appropriate persons. Such presentations do _not_ need to fulfill the above criterion, as the goal is simply to make sure certain information is disseminated to new employees and that they have a chance to ask questions. A speaker at such a presentation is not pressured to make it seem interesting and unique, but you emphatically are. Consequently, you must avoid modeling your talk after that mold. Unfortunately, many speakers do exactly that - they sleepwalk through the presentation with the predictability and the enthusiasm of a reference manual. They may be making no mistake by the book. Dark, appropriate suit? Check. Stand on both feet? Check. Look at the audience left, straight, and right? Check. Take questions? Check. Finish on time? Check. However, not making a mistake does not mean everything's well - you must have something to say, and something powerful at that.
I once attended a conference talk given by a gifted and experienced speaker. Unfortunately, I didn't enjoy his talk at all - I found it boring and hackneyed to the extreme. As I'm friends with that speaker, we talked over dinner the same day and I delicately shared my impression. He immediately admitted that the organizers had asked him to give a talk in exchange for free attendance, so he picked a subject, read some about it, and prepared the talk. It was all a mercenary job, and for all his talent and experience, that fact oozed through unabatedly.
So walk in with the certainty that you have something to share that the audience will be interested to hear from you. Have that message loud and clear in your mind as you prepare and deliver the talk.
A public talk is a social interaction and consequently some social dynamics are at work. Most of the fear of public speaking, particularly for first-time speakers, stems in the ultimate social stigma - being ashamed. You may say something dumb and they might laugh; someone could point out some fatal mistake you are making; you may trip and fall, burp, or fart during the presentation. And so on.
The good news is that as the appointed speaker you are in fact starting with a good deal of credit. If you think of it, you haven't seen many or any talks in which the speaker was ashamed. On the contrary, you might remember that audiences have been invariably polite and helpful, particularly with initially nervous speakers. The truth of the matter is that, all other things being equal, people would rather feel good than bad. Comfort and discomfort are highly empathic feelings - they propagate from the speaker to the audience. Consequently, the audience is inclined to forgive some initial awkwardness and to be helpful and non-critical towards a speaker. A comfortable speaker helps a comfortable audience, and that's what everybody wants.
Bottom line is, you don't start the game with zero points. You start with good credit and you benefit of people's natural inclination to enjoy themselves and consequently your talk. The dice are already rigged in your favor.
Stage fright is an irrational fight-or-flight psychosomatic reaction to the perspective of public speaking. I sometimes experience it, and I know very experienced speakers who also do. Most often stage fright consists of faster breathing, accelerated pulse, thirst, jumpiness, and muscle contraction. In turn, the contraction puts pressure on the vocal chords and makes your voice harsher and of higher pitch.
A good advice to fighting the stage fright is to cancel the symptoms: walk slower, breathe slower, drink water, and try to control your voice. That does work; at one point I got a terrible stage fright while walking from the back of a 500-person-strong room all the way to the podium. People were turning their heads and I was thinking, "what do I have to tell these people that they could ever find of any interest?" Amazingly, slowing my gait did it for me: I simply walked slower, and with each slow step my confidence and calm rose. By the time I made it to the stage, I was already in shape to deliver the talk.
But it is inevitable that sometimes such voluntary control is not sufficient. Fortunately, there's a secret you may not know if you're a first-time speaker: stage fright does go away. It just takes a bit of time, and since you're aware that it will go away, a virtuous circle of sorts will make it go away even faster. Once you start, simply ignore all the symptoms and go for it. The stage fright will vanish.
Incredulous? Find online some video of a famous speaker's talk. Examine their voice and body language in the first 30 seconds, and then fast forward to mid-talk. Very often you'll notice perceptible differences in voice pitch and body language.
Most of us have stage fright. Plow straight through it. It will disappear.
People normally listen to music at 1-3W of audio power. However, they prefer to buy more powerful amplifiers. This is because a 3W amplifier playing at 3W sounds much worse than a 20W amplifier playing at 3W. The dingy amplifier is already at its limits; it introduces plenty of distortion and lacks dynamism and clarity. This is because it doesn't have any reserve power left.
Similarly, you should develop an understanding of your material that is way above and beyond the stuff you actually present. The actual talk should dispense only about 10% of what you know about the subject. That, and only that, gives you reserve power. What's that good for? First, it helps you handle questions saliently. Many questions will inevitably push beyond the borders of the presented material, so you should have extra knowledge to handle those. Second, reserve power gives you the liberty to adapt the material to your audience. Third, it allows you to better drive your point through effectively - because knowing more is also knowing what can be safely left out.
For example, I once gave an invited talk to a group of undergraduate students. The talk was about some advanced topic and began by briefly presenting some alternative approaches that were wrong or unrecommendable, each for different subtle reasons. It didn't take long to figure that the students weren't aware of the fallacies of those approaches. That wasn't a problem with their preparation level; they simply hadn't been yet exposed to large-scale software that allows certain phenomena to occur. Consequently, that made it impossible to make them appreciate the gist of my talk. So I decided on the spot that my talk will be essentially the expansion of only one slide of the initial presentation; starting from that slide and with the help of a whiteboard I discussed a range of topics that they found informative.
The point? Knowing minute details of the topic involved allows you to take the talk any direction the audience wishes. Many of us are often tempted, when preparing slides, to insert some helpful material that we don't know much about but is present in the community lore. "Possible approaches: X doesn't work, Y doesn't scale, Z is inefficient." Without exception, you must resist that temptation. A mental image that I enjoy is that I should be able to take any bullet point in any of my presentations and defend it in a court of law. Be very strict about this principle, it helps your reputation.
Master your material beyond the limits of your presentation. There is no substitute for knowledge, and since you're the speaker, it is your primary duty to be knowledgeable of your topic. Be ready to expand on each and every single statement in your slides.
You know your material perfectly (because you've internalized point 4) so approach your talk from a frame of total confidence.
Confidence is an odd beast. Many people confuse it with self-esteem, so if they have self-esteem (as many good hackers do) they think they're in good shape. In fact the two notions are distinct: self-esteem is related to your perception about yourself, whereas confidence is (careful here) your perception about others' perception about you. If you think you're okay, you have self-esteem. If you think others think you're okay, you have confidence.
People may have one without the other. The stereotypical high-confidence, low-self-esteem person is the big-mouthed jerk who deep inside fears being a fraud. Conversely, the shy geek who could get a date "if only she really got to know him" has good self-esteem but low confidence.
Confidence is also not arrogance. Confidence is about your value as perceived by others. Arrogance is about your value in direct comparison with others. Confidence is a claim that you're good; arrogance is a claim that you're better than them.
You need to be highly confident to give a good talk. Your confidence will make you poised and relaxed and will inspire trust and calm to the audience. Of course, knowing your material is a prerequisite for acquiring confidence - that's why point 4 mentions there's no substitute for knowledge. But you need more - you need to ooze ultimate comfort with the situation.
Fortunately confidence is one of those "fake it til you make it" traits. Heed the advice at point 3, acquire the body language, the attitude, and the thoughts brought about by confidence, and before you know it you'll have it. Don't get all-important; you didn't solve NP-completeness. Relax and convey your enthusiasm the way you would with a friend and peer: passionately and convincingly, yet humbly.
This is a popular public speaking tip, but it is often left too vague to be useful. Without detail, such a notion evokes some sort of warm and fuzzy feeling that somehow should magically emerge between you and your audience.
I define connecting with your audience in a very pragmatic way. First, you must develop very early and very acutely an understanding of your audience's background as it relates to your material. Second, you must engage the audience at key points in your talk by asking them questions and generally interacting with them.
I've seen many speakers not realize through an entire talk that they assumed the audience knows stuff it didn't, or, equally bad, assume the audience lacks a certain background.
Solution? Simple. Ask your audience. I very often start a talk by asking for a show of hands. "How many here use language X/operating system Y/technology Z in their daily work? How about W? T or U, anyone?" (Always ask in positive, not negative terms.) Asking the such has in fact saved my day on more than one occasion (such as in the example I gave in the previous section); often, the show of hands would indicate the talk as planned wouldn't be entirely appropriate, so I'd need to stress on certain aspects and pedal light or omit others.
Staying connected has many other advantages - it's a win all over the place. It engages people and encourages them to get involved. It makes them more attentive. It makes them feel you care about what they know and what they think, and that you are making efforts to convey information they'll find valuable. After a good talk, an attendee should ideally feel like an active participant instead of a passive recipient.
Interacting with the audience will munch into the time allocated for the talk, and may become of limited usefulness if e.g. 1-2 very active participants monopolize the interaction. It's not difficult to keep control of the situation - just do what they do at press conferences: never have the same person have two shots in a row. Also, explicitly elicit interaction from vague groups who have been silent. I always insert a joke like: "Right-hand side, any opinion on X? You haven't talked to me much yet."
Connecting with your audience may be made difficult by various circumstances. You may be on a stage or podium that puts a distance between you and the audience, or the audience's culture may deem interruptions rude (happens often in Asian countries), or the event may be videorecorded. In such cases, work with what you have. You can always elicit a show of hands. Often you can make a bold move - it has happened to me to go off the podium and briefly hand the microphone (thank God for wireless mikes) to someone in the audience. Remember, people are already inclined to view favorably a slightly unusual move on your part because of point 2 above.
Connect with your audience and stay connected through your talk.
Good time management is an absolutely essential feature of a good speaker. Handling time is very difficult, and many otherwise excellent speakers fail at it in various ways.
First off, make it an absolutely immutable rule that you finish on time. You may think there are exceptions (e.g. no talk after yours) but there is virtually no circumstance in which you can ignore that rule, and here's why.
Each person attending a talk makes a mental plan prior to the talk, sets a sort of internal countdown. "I will sit through this talk until it's done at 3pm, then I'll call my spouse to ask about our hamster's existential crisis." Or whatever. The time limit is a powerful social contract between the speaker and the audience: the talk, good or bad, will finish at a specific time, at which point the day can continue for everyone.
The timely end of a talk is a perfect climax shared between the speaker and the audience. You say what you had to say, you're done, it's 3pm, and everybody's happy. As in other situations in life, finishing right on time is the best option.
Clearly, there are many situations in which post-talk spooning is recommended. Often you may be giving the last talk of the day or there might be a generous break before the next talk. In such cases, you may want to announce that you'll hang around for taking questions and for a free discussion for anyone who might want. That's great - the social contract has been fulfilled, the shared climax has been reached, and you can enjoy some relaxed time together with your audience.
Finishing late can be extremely rude. A friend of mine was to give a conference talk, but the speaker just before him wouldn't stop. My friend kept on gesturing and pointing at his watch, until he had to stand up and say: "You're fifteen minutes into my talk!" Incredibly, that jerk got mad at him - talk about adding insult to injury! My friend's time slot was timeboxed; lunch was right after it, so he could only use less than two thirds of the allocated time. Needless to say, his talk was a fiasco.
Now, assuming you are convinced that you will always finish on time, I have some bad news: it's not only about finishing on time - it's about managing your time throughout the entire talk.
I recently attended a 90-minutes talk - a conference keynote - by a very engaging speaker. He had a funny intro and many anecdotes to share but after 80 minutes he was like, "Rats! We have 10 minute left and we just got to the meat of the talk!" He then tried to machine gun through the slides, and of course that didn't help the situation one bit. The talk had started great but ended with a fizzle (albeit on time).
You must constantly keep in close check the balance of time and that of the material. Things can get out of sync for any number of reasons, most often questions from the audience (which are otherwise good per point 6, so don't discourage them). If things get out of sync significantly, make an executive decision and always announce it in a poised manner. "Since we got so excited about topic A, I will skip the following five slides discussing topic B. You can always find about B in the distributed handouts, and feel free to contact me offline with questions. Let's move on to topic C, which I believe is interesting to discuss at this point." That always works - it shows the attendees that they have access to the information and also reassures them that you're in control of the situation.
Time management is very difficult. I don't have a recipe to recommend. Certainly sheer experience does help. Rehearsing your talk alone gives you a baseline, but it's not that helpful because, as discussed, your talk should not go as rehearsed almost by definition. A dry run in front of a small audience is highly recommended if you can arrange for such.
Time management is also extremely powerful. If you have a good grip on time, you can create anticipation - a powerful psychological device. "Finally, X is most adequate in conjunction to Y. I know that sounds a bit odd, but I'll explain that relationship in a few minutes." The attendees get reassurance that you have an image of the temporal unfolding of the talk and also have their curiosity piqued.
Learn to have a notion of the time balance at any point during the talk, and make and announce executive decisions regarding skipping material if push comes to shove.
Look at them. Twenty, fifty, one hundred, or one thousand persons sitting there and waiting for you to wow them. You have your material. I'm sure it's wow-worthy, but that wow can be extracted by reading an article. What really makes those people come and listen to you is the extra umph - the experience you're providing. A talk is not a presentation - it is nothing short of a creative endeavor, and you should think of it that way.
The band Queen was famous for its great concerts, which have broken a number of audience and sell-out records and also received unanimous critical praise (culminating with Channel 4's best live act in history award for Queen's performance at Live Aid in 1985). What was the band's secret? At a time when most singers and bands would focus, in concert, on playing each song close to the reference recorded versions, Queen would deliberately approach each concert as a unique event (the whole show experience, not only the play list, would matter); they would never lip-sync, and they would never attempt to imitate themselves. They played their songs at their best right then and there, for that public. That's what made each of their concerts memorable.
I'm not saying you should grow your hair or make your entrance on a guitar riff. But do approach each talk as a performance of your material that will turn as unique as you and your audience can make it. Simply remembering this is very powerful because it puts you in the right frame of mind. Many talented hackers give boring presentations because they aim for the standard "let's make no mistake" presentation style. They have interesting material, elaborate slides, but they are content with giving a presentation. You should produce a performance instead.
In giving a talk you must put your enthusiasm, eloquence, humor, and general creativity to work. That's what makes your material come to life, and that's what the audience will remember mostly about you.
To give a good long talk on a technical topic, have something to say; understand that you are starting from a favored position; plow through your stage fright without paying attention to it; accumulate much more expertise in the subject than what you're disseminating; establish a frame of confidence; connect with your audience; manage your time; and don't forget you are there to give a performance, not a presentation.
Scott Meyers has shared great insights and tips with me. He suggested Point 8. I'd also like to thank Leah Pearlman and Brad Roberts for their contribution in preparing this material.