Having seen countless good and bad PowerPoint presentations and produced several of my own, I wanted to publish what I consider the most important rules of PowerPoint presentations.

1. Respect your audience. Once, I was part of a group that was refining several presentations for a conference. Upon seeing one slide rich with data, the leader of the group told the author to "dumb it down" to only the "takeaway bullets". When I asked why, his response was that the data would confuse and overwhelm the audience. In retrospect, I am firmly on the side of Edward Tufte. Do not treat your audience with contempt, like idiots with miniscule attention spans. Do not insult their intelligence by forcing your conclusions down their throats. Instead, lead them to those conclusions by presenting complete data transparently and describing your reasoning.
2. Minimize the number of words on each slide. This has to be the most common problem I see with PowerPoint presentations. Usually, it is because the presenter is too lazy to produce separate speaker notes and documents for the audience to take away, in addition to the slides. So he ends up with a single file intended for multiple purposes: to remind him of what to say, to supplement what he says, to give members of the audience a record of what he said, and to give people who couldn't attend the presentation a useful substitute. During the actual presentation, the presenter either reads what is written on the slides, which is a useless waste of time, or says something slightly different, in which case the slide distracts the audience from the speaker and the speaker distracts the audience from the slide.One reason people do this is that many of us learned our presentation skills in school before PowerPoint was even invented. We were taught to prepare an outline and then index cards and then deliver a speech. PowerPoint lends itself very well to this approach. But we were never taught to blow up our index cards into posters or project them on the screen, so why do we do it? The only answer I can think of is that the modern conventions of presentations demand a screen full of something while we are talking. Putting too many words on a PowerPoint slide has one other problem: the more words there are, the smaller they must be to fit, making them harder to see. Each line of text becomes longer, straining the eyes as they move over it. Replace words on slides with pictures or illustrations. Don't describe it--show it! The human visual system can absorb a picture far more rapidly than a passage of text, and the audience can then attend to the speaker. Another great technique is simply to blacken the screen for sections of the presentation that are primarily oral. Perhaps the conclusion is: "Less is more." whether you consider the number of words on each slide or the number of slides in the presentation. An interesting variation on this theme is the famous presentation on Identity 2.0 by Sxip CEO Dick Hardt. Here, the slides contain a few words at most, and serve to emphasize the speaker's words.
3. Use subtle effects intentionally. PowerPoint makes it far too easy to put dramatic colors, fonts, transitions and animation effects in your slides. Presenters often use these as a crutch because their presentation lacks emotional appeal. Avoid these except when the effect itself serves to communicate, and choose subtle effects.
4. Three E's: Engage or draw people's attention to your presentation. Entertain them so they feel the time spent was worthwhile and enjoyable. Educate them so they go away with something valuable they didn't previously have.
5. Practice practice practice.