[pariya]

Whenever I give a talk, I show up wearing fancy lingerie underneath my business clothes. That way I get the feeling that I know something absolutely nobody else in the room knows... and that little fact gives me confidence.

If you're a guy and/or not into wearing lingerie you can always wear a ridiculous shirt underneath your presentation clothes that has something outrageous on it. Or (if you're crazy enough) put a printout of something random, like a banana or a hamster or Oscar the Grouch in your pocket. Just thinking in the first ten seconds that you did something so nonsensical make you kind of wonder if you are losing your mind- in which case you may have a little chuckle to yourself, causing the tension to dissolve. Also, you will know something the audience absolutely doesn't.

I realize this is exceptionally unorthodox advice, but it works so don't knock it 'til you've tried it.

Another tip is to pretend that you are talking to a room full of friends, that you have been accepted by all of the audience members already and they support you. Takes the edge off...

jsonne is absolutely right the lead up is always worse and after 10 to 20 seconds it starts to feel normal.

Knock 'em dead, you're gonna kill it.