It's been almost 15 years since my first game. (That's so depressing.) But I have done a "first game" at a couple of different levels, moving from sub-varsity to varsity to college ball. Each level brings new butterflies, that's for sure.
At this point, the thing that helps the most for me is arriving at the game site EARLY. This gives me the chance to do several things. I can read my case book or talk to my partner(s) to put me in a basketball frame of mind. If my partners aren't there yet, I can close my eyes and just try to rest a bit (this is nice in the middle of those 10-games-in-11-nights stretches). If there's a JV or women's game before mine, I can watch that game. (That doesn't always help with the basketball frame of mind, though.
) Or I can listen to a recorded pre-game that I have; which I usually listen to in the car on the way to the game.
The worst thing in the world for me is to be late to the game site. I am rushed; I'm worried about getting there; I don't have the chance to think about the upcoming game.
Best of luck!