Scott Hanselman posted a list of speaker tips for technical presentations. It's a great read, and so are the comments.
Here are 10 more tips to add on to his, focusing on general presentation skills. In my job I have the opportunity to speak with many different people in a variety of settings. I've found the following tips to be useful in most situations, whether delivering a high-level presentation to a small group of C-level executives, or a technology deep-dive to hundreds of developers at a large conference. I hope you will find them useful as well.
#1 - Speak Clearly
Speak slowly and clearly, project your voice, and break your sentences into phrases. It's amazing to see how many people talk too fast, or let their voice trail off at the end of sentences. Talking slowly will not only make it easier for your audience to understand you, but it will also help reduce the filler-words ("um", "ok?", "right?", etc.). When you speak slowly, you have time to think about what you want to say, and to "queue up" the words so that they flow smoothly. Speaking slowly and deliberately replaces the filler words with short pauses that give people time to grok your previous sentence. It also helps non-native speakers (people whose primary language is different than the one in which the talk is given) keep up with you. Beware of overdoing this though, or you may sound like a lecturing professor :-) Speaking slowly also lets you breathe more easily, which would help address the "trail off" problem, since one of its causes is simply running out of air.
#2 - Tie the Content to Something That the Audience Can Relate To
As techies, we are often engrossed with the neatness of the solution that we have built, or the technology that we are explaining, and when we talk about it we sometimes forget to explain to our audience WHY this great piece of technology is important to them, and the value that it holds for them.
Tell them an end-to-end story. A good pattern to follow is to start with either the state of the art, where things are today, or where we all want to go; nothing too controversial. Then continue to detail some of the pain-points, issues, or things that are hard to do today or that stand in our way of attaining that vision. Then show how the stuff that you talk about addresses these issues, by tying every point that you're making back to the original set of issues or scenarios that you presented. This approach doesn't fit all situations, but the model behind it is a classic "story model", so just go ahead and adapt it to your needs.
#3 - Rehearse, Rehearse, Rehearse
A talk is very much like a show. You are on stage, in front of a live audience, and you have a script to guide what you say and do (although you might be improvising around it). Just like a stage show, your talk should be well rehearsed. Ideally, you should know your talk by heart. You should be able to give the entire presentation from memory. The slides are for the audience, not for you. Know all the talking points, have the demos polished and smooth, and know where you want to be (time-wise, audience-emotions-wise, and story-wise) at key points in the presentation.
#4 - Think About the Emotional Impact of Your Talk
At a conference, people change context every hour. By the time they leave, they will have seen over 20 talks. How will they remember yours? People describe talks as "boring" or "cool" - they describe their experience in emotional terms. As it turns out, most people don't remember a lot of the technical details of talks they have seen, but they will remember their "wow!" moments, and how they felt at your talk. Move your audience.
Humor may at times be a dangerous path to walk (especially cross-cultures), but done right it will take the talk to a higher level. You can use spoken humor or funny graphics on your slides, but be culturally and environmentally aware. A much safer path is a cool demo with a suspenseful moment or something that people do not expect to see that will get them applauding spontaneously. If you can pull off a "wow!" moment, spontaneous applause, and a laugh all at the same talk, you are a true presentation master :-)
#5 - Engage With Your Audience
Always look at and talk to the audience. You are there to talk and interact with them. Catch people's eyes for a short while, and give audience members the feeling that you are talking with them. Beware not to look at one person too much or for too long of a time or that person might feel as if you are putting them "on the spot". Similarly, beware not to look at a person for too short of a time, or that person might feel as if you are trying to avoid them. If you are indeed speaking in phrases (tip #1), look at an audience member for one phrase, then move on to another person for the next phrase. If you are too shy to look at people in the eye, look at their forehead - they could never tell the difference :-)
Remember to give proper attention to all parts of the room. One good way to do that is to split the room into quadrants and scan them in a figure 8, choosing a different person to look at every time. One nice trick to get used to doing this naturally is to do the following when practicing your talk: place post-its on the wall with eyes drawn on them to simulate the audience, and then practice eye contact and the scanning pattern while you practice delivering your talk. Moving about (see tip #8) will also contribute to your ability to pay attention to the entire room.
Do not talk to your slides being projected on the screen behind you (see tip #3). You can glance at the screen for a second to make sure that the PowerPoint animation is happening as expected, but don't talk with your back to the audience. It doesn't matter if you're looking at your laptop's or the podium PC's screen either - if you're not looking at the audience you're not talking to them.
Speaking of computers, do not talk to your computer. If you are demo-ing something and need to operate the computer, make sure to look up at the audience every few seconds, and maintain that eye contact. It is most likely that the audience would be looking at the screen and not at you, but you still want to look at them (see tip #6).
#6 - Be Attentive to the Audience's Feedback and React Accordingly
Whether you're giving an intimate talk to a handful of folks, or presenting on stage in front of hundreds of people, be attentive to your audience's verbal and non-verbal feedback. Look at them continuously when you talk (see tip #5) and ask yourself:
Whatever you see, don't just plow along your predetermined path. If something works with your audience, do more of it. If something doesn't work for them, stop doing it. If the audience isn't laughing at your jokes, drop the humor. If they like code, stay in the IDE and talk to the points that you have on your slides from memory (see tip #3). Remember that at the end of the day you are there for them, and if you want them to like your presentation (see tip #4) you need to give them what you want in a way that they like it.
#7 - Use Hand Gestures and Other Non-Verbal Communication
Use your hands to gesture in a manner that complements and augments your verbal communication. Here too, you should be aware of cultural differences and sensitivities. Some motions do not cross cultures, e.g. making "bunny ears" with your hands to signify quotation marks while you speak. Some motions that are benign or even friendly in your own culture (e.g. showing the palm of your hand) may be offensive in others. Large motions, those done with your arms rather than your fingers, are typically safer than finger motions, and can also be seen better by people sitting far from you. One specific thing that I need to do fairly often is point at people to indicate their turn to speak. If you need to point at someone, a culturally safe way of doing that is with your entire palm, rather than by pointing a finger. Motion with your palm facing upwards as if you're inviting the person to speak, rather than pointing and putting the person on the spot. Lastly, when you are not gesturing, relax your hands to the sides of your body and assume a natural pose.
#8 - Do Not Stand In One Place
Move on stage; be energetic and dynamic, but not erratic. Move with a purpose. Do not wander or drift, and remember to replant yourself after you move from spot A to spot B. Allow yourself a few moments in a location before moving again. One thing that I sometimes do is associate certain spots on stage with something that I'm talking about. For example, I'll stand at one point of stage when talking about the developer aspects of something, and at another point when talking about the user aspect of that thing.
Do not "hide" behind the podium - step out to the open where people can see you. When possible, I enjoy walking down to the audience and talking with them up-close. This is not appropriate for all presentation types, so use this advice cautiously. Also, if you are using a microphone and plan to get off stage, first make sure that there's no feedback. (Try it out at the tech-check and figure out the "safe range".)
Josh Holmes has a good post on this as well.
#9 - Simplify Your Language and Grammar
Language mastery is the mark of the erudite. It is, however, an impediment for non-native speakers that hinders their apprehension of the information thus conveyed. Let me try this again: Speaking a language very well may show that you are smart, but it does not help people understand you better :-)
#10 - Relax!
A relaxed speaker seems more confident, knowledgeable, and in control. Being relaxed will help you better remember your talking points, and make it easier for you to focus on multiple things at the same time (the content, the audience, your stance and voice, etc.). It will also help you keep your cool and recover gracefully as the inevitable presentation "hiccup" happens every now and then. Get a good night's sleep before your talk. Cramming the night before and being tired for the presentation is not going to make it any better. Practicing and being prepared for your talk (see tip #3) will also help you relax. Clear your mind of all other distractions and get into what I like to call "Presenter Mode".
That's it for now! I hope this will be helpful and do let me know (via comments) if you have any other tips and tricks to share.