I've always been a fan of keeping things simple. When giving a presentation I prefer to keep my PowerPoint simple and use it to emphasize just the key points. In fact there is a gentleman who has obtained some notoriety for his use of slides that only contain one word on a white background. Going one step further, you might consider leaving the PowerPoint at home in some cases. What I consider to be the best speech/presentation I have given was done last year without any PowerPoint at all.
The following short, and entertaining, video does a great job of teaching you how not to use PowerPoint. I'm sure you will find plenty to relate to; hopefully as a audience member and not the person giving the presentation!