[dubious elise]

No matter what, stress and the way you handle it does play a large role in the game. Our drive team this year usually just talked to people (refs, other drive teams, pit crew members from our own team, each other) to stay cool or watched the matches. The best advice I can offer is to enjoy yourself as much as you can. As awesome as it is to win, you have to remember that there are things infinitely more important than winning; hence the reason that there are so many spirit, design, and community involvement awards.
Personally speaking, I tend to be a complete ditz at competitions. Not intentionally, persay, just in the sense that I make myself completely oblivious to the importance of each and every match. Though I can perform well under stress, I also make more mistakes - being comfortable with your role before you actually get into a competition helps immeasurably. Hence, if I convince myself to not take every match so seriously, I will perform just fine!