Keep it Simple
PowerPoint slides shouldn't steal the show—nor should they be a complete script for the presenter. They are meant to emphasize your key points in a visual way.
To give your point emphasis, float it in a sea of white space. Remember that the less information you put on your slide, the more clearly your message will come across to your audience.
Resist the temptation to resort to slide after slide with bullet points, also—since studies suggest that this format is one of the fastest ways to lose your audience.
For example, look at these two slides from a presentation by João Paulo Alves on simplicity: