Do not print out your PowerPoint presentation and use it as hand out material. If you do this, your audience has no reason to look at your PP up on the wall. If they're looking in their laps, they're not looking at your PP, and they're certainly not going to look at you up there next to it. And, if they're not looking at you, they're sure as shit not listening to you.

As a matter of fact, eliminate as much text as possible from your PP if you're lame enough to be using PP. YOU are supposed to be giving a presentation, not the overhead projector...

Know your material well enough to have a casual conversation about it. If you can do that, you can deliver your entire presentation without looking down at your podium. This will engage the audience and make them feel as if they are a part of a conversation, rather than being lectured. Keep it light but informative, comfortable but riveting, and you can only do this by knowing it like the back of your hand.

Practice as much of it as possible, and every time you say "um" or whatever other conversational tick you have, kick yourself in the balls. The wincing and writhing on the floor will make you look as stupid as you sound when you say "um" over and over again. Every time you do that, you lose your audience. It's like storytelling. When you make the reader think about the story, you take him or her out of the story. When that happens, the books is likely to be put down. Don't take your audience out of the conversation you just tricked them into thinking they were a part of by sounding like a dumbass who doesn't know what he's talking about.