PowerPoint mistakes that drive people crazy
Bad entrance, bad exit
Treat each slide as a mini-presentation. Don't jump right into the details, give us an overview first. And at the end, tell us the point.
Also, if you're not going to use another slide for a while, darken the screen. My favorite PP trick: press the "B" button to make the screen black. Then press "B" again when you want it back on.
If you do.