It's been a while since I've played in OTB tournaments, but I've heard that the night before the tournament (and maybe even the day of) it's good to do visualization training to stretch your mind. Here's a link to a place that does that: http://www.chessvideos.tv/chess-visualization-trainer.php Since this is week long tournament, you might do it every mourning before your play and everynight after you're done, sort of like how you stetch before and after exercising.
Also and especially if you're playing an IM, go over the game with your opponent when you finish playing. You can get a lot of good advice that way.
Decide what openings you want to play before you start play, it can save you time and stress during the game.
Finally, when it's not your turn, relax, take breaks, get up and walk around. To much mental concentration can wear you out quickly.
Two days from now I'm gonna play the first round of my first tournament. The time control will be 90|30. It's an open event and I'll be glad to be paired with an IM or something, although I will get my ass kicked for sure. There will be 9 rounds and it will last a week. Any last advice would be appreciated