Just try to play as good as you can. Read up on tournament strategy, maybe play some low BI MTTs to practice concepts you are unsure about (3/4 betting PF, floating, barreling etc.)
You should really try to go into the game without being "scared" or "under pressure" if you know what I mean. There are moves you should make, and you should be ready to do this.. Dont play passive because it is a good ticket.
My best advice would be "You are in it to win it". Fold, call, raise. lol.. AT the right time. Prepare as best you can, then, when the game starts, play your best.
I know this is not concrete at all, but just be as prepared as you can be, then you just have to play. Try to notice player tendencies. Try to estimate ranges. Play good!