I totally agree about the good night's sleep. I hardly slept a wink the night before my first HS game, and I
SUCKED. YMMV
Advice: Slow down. When you think you're going slowly enough, slow down some more.
Don't be afraid to talk to the players or the coaches. But do keep your replies to single syllable sentences.
The nerves will go away once the game starts. Once the toss goes up, it's just basketball (although likely to be a little better basketball than you've been seeing)
Have some fun