I came across a post by Kathy Sierra about her approach to presenting. This part stood out to me:

Open with a question they would very much like an answer for.

That’s it. Pose a question. You don’t have to announce you’re going to answer it, just… start. If you’re looking for an opening phrase, try something like, “Imagine you want to…” and then go. Don’t hesitate. And whatever you do, do NOT try to “establish your credibility”. Never try to tell them or sell them on why they should listen to you. If the question is one they want answered, their brain won’t let it go. The rest of the presentation is just a steady reveal of the answer(s).

There’s a lot more great stuff in her post, like focusing on making the audience more awesome, instead of being in a race to be the most awesome presenter. If you want more, check it out here.