I used to do a lot of public speaking competitions when I was in school - prepared speeches, impromptu speeches, debates. Along the way, I learned a few things about getting up and talking to a room full of strangers.
1. Eye contact is good. But forget the ol' adage about picturing people naked. I can think of few things more distracting when giving a speech or workshop. Here's what I do, especially if it's a big crowd. I look just over people's heads. Looks like I'm looking at them, but I'm not.
2. Instinctively raise your voice by looking at the back wall. This tip came courtesy of the late True Davidson who was one of my contest judges.
3. Move around. Not a lot, but some. Few things are more boring than seeing somebody stand in the same place for an hour.
4. Avoid fussing with glasses, jewelry, your water bottle, papers...anything, really, that makes folks start to pay more attention to what you're doing than what you're saying. I remember one workshop where the speaker kept unscrewing, then re-screwing, the lid of her water bottle. Just about drove me nuts and I have no memory at all of her workshop except for that.
5. Rehearse, but not too much. You want to sound competent and in command of your material, but you don't want to sound like a robot.
6. Wear comfortable shoes and clothes. This is NOT the time to wear those fantastic new pointy-toed pumps. Or that shirt that looks good, but makes you itchy around the collar.
7. Most importantly, try to relax, especially if it's in a workshop environment. People want to hear what you have to say, or they wouldn't be there. And having been to several workshops myself, I can tell you that you really have to do something pretty foolish to earn the enmity of the
room. Nervous? That's fine. We sympathize. Lose your place? Laugh and get back on track, and it's all good. Don't have the answer to a question? Admit it. Nobody expects you to know everything. Slam a genre in a roomful of readers and writers of the genre? That's just plain foolish. But you really do have to do something that extreme to lose the room, so try to relax, look at the back wall, move around a little, and enjoy the ride.