To get you started, here are a few recommended books:
Beyond Bullet Points by Cliff Atkinson (ISBN: 0735620520) 2005.
This is a superb book describing an audience-centered approach to creating and delivering PPT presentations that is based, in part, on Richard Mayer’s research into multimedia learning. I HIGHLY recommend this book.
Presenting to Win by Jerry Weissman (ISBN: 0130464139) 2003.
Another highly-recommended resource which incorporates best practices and guidelines from broadcast journalism and tv production. Easily read on a cross-country flight and well worth it.
For more on the visual design of your slides, check out:
Before & After Magazine. http://www.bamagazine.com/ Subscription: $24.00/year PDF.
Seriously, whether you are an expert designer or a novice PowerPoint user, each issue of this magazine offers superb ideas for website and print design which (with a little bit of your imagination) can easily be adapted and modified for slide design. (Any of the Before & After books are also useful).
Chuck Green’s Ideabook. http://www.ideabook.com/.
Similar in scope and content to Before & After, this is another great resource for getting design ideas that you can apply to your slides.