If you use Powerpoint, a few principles and tips to keep in mind when using type on a slide:
Don't read the words. It's bad enough that people use Powerpoint as a sort of teleprompter. Much worse that you don't trust the audience enough to read what you wrote. If you want them to read the precise words, stand quietly until they do. If you want to paraphrase the words, that can work.
Big font, few words. And use pictures. Your narrative is the message.
Words on slides by Seth Godin