Jeff Atwood at Coding Horror has a snide and spot-on post on how not to do presentations. I have sat through far too many presentations and briefings which hit the majority or all of his rant points.
Do yourself a favor if you’re presenting: be familiar with some of the presentation best practice tips out and around. Look at great presentations by folks like Hardt or Lessig. Spend time at Beyond Bullets. Understand Atwood’s great points. Grok out the stuff at PresentationZen.
Perhaps most important: think about the bad presentations you’ve been to, and why you thought they sucked — and then do something better.