If you can't answer the four W's, and tell a story about it, stop wasting other people's time...
I've sat through my fair share of presentations that are not only disrespectful of my time, but make those presenting look stupid, to say the least.
Presenting doesn't just happen for most people, and audiences will rarely tell you how bad you were. Invest in a digital video recorder, and a voice recorder. Rehearse! Write a script, but never ever read through a presentation.
Deliver a clear & emotional moment, or you will just look stupid. This does not mean dumb it down for everyone [they might be unprepared], but if your diagrams, body language, but particularly, passion are clear, you will get a long way. Please, be strategic.
Believe in yourself & the message. If you don't, neither will others.