1. Remember that PowerPoint is used to enhance the lecture material, not to simply repeat it. People read faster than you can speak; when you use just words (and I am guilty of this as much as anyone else), students will read, write and simply wait for the next slide. There is little engagement there.
2. Keep the information on a slide to a minimum. Have you ever sat in a conference while someone projected a slide with 20 lines of text on it? What is important in that mass of text? Can it be read easily? Keep it simple and to the point.
3. Forget about using all the tricks that PowerPoint offers- do not use transitions and animations from slide to slide. These take time and interrupt the flow of information. They add no information to what is being presented, and are really the mark of a novice.
4. Make sure your slides are easily readable. Not all designs are the same. Some are busy or use odd color combinations. The new template slides from marketing are excellent in ensuring that what is on them can be easily read.
5. Practice your presentation. Do not go in de novo and expect to be a master at your presentation. For conferences, in particular, it is important to anticipate time spent on presentation. I always think I have plenty of time, and I almost never do. Practice makes perfect.
6. The audience should be looking at you most of the time, not the slide. There are many good books on how to make this happen, but relying on fewer slides, and with less text, but more pictorial elements, will help. Think of TED talks, for example.
7. Make sure your version of the program is compatible with the computer and projection system that you will be using. This is critical in conferences, where you can lose embedded movie clips, mp3, etc. because they are using a more modern or more outdated version than yours.
8. Use black slides every now and again- no text means they have to focus on you instead.
9. Finally, speak well and clearly. Rely on yourself, not on the slides.