Even though I hate the sitting through meetings where this product is used; I found this article
"8 mistakes when creating PowerPoint presentations" by SympleByte to br right on target. There are a couple of basic mistakes here but others that anyone who ever has to use PowerPoint (or use slides to deliver a presentation) can learn from.
I'd also recommend reading
Guy Kawasaki's "10/20/30 Rule for PowerPoint" in order to get the structure of the presentation right.