I get nervous too (though I've only been to two competitions). Similar to Dene, I really only get nervous when I want to get a good time. I get nervous at home when I want to get a good time.
I completely agree with qqwref, and I'm not saying that to make you get self-conscious about if we think you are slow/fast. It's honestly the flat out truth. Every competition has that person or people that people expect to win, and they will be watching them. People practice pretty much all day, between solves, between rounds, etc. You'll see people racing each other for fun, doing the 50 cube everybody solves a cube til we're out game, etc.
My best advice: Don't worry a bit about the times you get (unless you are sub15). Focus a lot more on everybody you get to meet because there will be puzzles there you've never played with. There will be people there you think are really cool. There will be cool fun games to play with all the other cubers, etc. The best thing you can do at a competition is not compete, but making all these new friends. All the silly games people do are usually a lot more fun than the times.
I personally want a sub20 average but I am trying to get out of practice all day so I can get good times. It's a lot more fun hanging out with everybody else.
