I have given many, many talks -- from dense technical presentations to generalized keynote addresses -- and have been doing it for over twenty years. Here, in my opinion, is the deal:

1. Don't start your talk by apologizing. "Well, first I need to apologize. I'm insanely jet lagged, and so I'm not sure how coherent this is going to be." "First, I'd like to apologize. This is actually a revised version of a talk I gave in 2009." "Let me start with an apology. I have a terrible head cold."

Just stop. If the talk is incoherent, you'll just have to do your best on the spot. If you're tired, too bad. If you think people might have trouble hearing you, say so. But don't apologize. People do this because they're nervous, not because the audience has been insulted or aggrieved in some way, and while it might seem like a friendly gesture, it's more likely to communicate that you're unprepared. Or nervous. And it's a cliche.

2. Do not ever go over time. In fact, go under time. As Edward Tufte once said, "No one ever left a presentation wishing it had gone on for another 45 minutes" (or something like that; you get the point).

3. Do not read your goddamn slides to the audience. Please. That is not "giving a talk." You can maybe do that if it's a long quote, but don't read the bullet points that everyone can clearly see right in front of them. Expand on them, provide counterpoints to them, whatever, but do not read them. If you're thinking of your slides (when you're creating them) as "what I'm going say," you're probably doing it wrong.

4. Use a laser pointer sparingly or not at all. Use it only to make a precise gesture necessary to point something out very specifically on a chart or map, and then shut the thing off. Making dizzying circles around every bullet point is incredibly annoying.

5. "Never mind the mic. Can everyone here me? I'm just going to speak loud." Unless you're very experienced with this (professional teacher, actor, or something like that), you probably don't know how to project your voice for twenty minutes. Get the mic fixed and use it. If the mic can't be fixed, speak way louder than you think you have to (without shouting). This is a learned skill, and most people don't know how to do it (but think they do). If the venue is large enough to require amplification, it's there for a reason.

6. Speak at a moderate pace. People speak fast when they're nervous. The proper pace will feel a bit slow to you, but perfectly natural to the audience. Check yourself periodically. Write it down on your notes. Slow down.

7. If some parts of the information you're trying to communicate are very dense or there's some useful data that will help to contextualize your presentation, create a handout. Do not try to cram it all into a slide.

8. Take some time to try to imagine every conceivable question you might get in the Q&A. You won't hit them all, and things do come out of left field, but you don't want to be caught totally off guard. Just review any common misconceptions or objections to what you're saying, and give some thought to how you're going to respond. Some people just want to comment. Thank them, briefly offer a comment if appropriate, and move on.

9. If you feel the need to ask a question like, "Does everyone know what a frubazzle is?" don't. If the question is warranted, then you can be absolutely sure that someone in the audience doesn't know what that is. Just say, "Some of you may not be familiar with the term, 'frubazzle.' A frubazzle is a . . ."

10. Commit to getting better and better at it. When I gave my first talk (in grad school), I thought, "It's going to be really embarrassing when I faint dead away in front of all these people," and I made a lot of mistakes. Today, I have only the slightest pang of nerves when I step up, and it goes away immediately. When you hear a good talk, try to figure what made it good. How did the speaker behave? How were the slides set up? Did they do anything that you can incorporate into your own presentation "style?" Public speaking is an ancient art, and you need to treat it as you would the art of writing or the art of coding: with care and study.