The temptation when using Powerpoint is to create and display diagrams.
Don't do it.
Diagrams may help you understand the problem and you should understand what you are saying. But don't display your diagrams. It takes too long for people to see and understand. They'll lose what you are saying in an effort to comprehend your bullets, arrows, and boxes.
Tell a story instead.
Display lone words and engaging pictures. Your slides will help signpost and illustrate your story.
As an example, take a look at this piece from The Wall Street Journal: Avoiding the Road to PowerPoint Hell.