Welcome to Gaia! ::

Hiya, i don't play the trombone, but i do play the trumpet, and i can help you with almost everything except the positions xd

anyways, my suggestion is to make sure your warmed up (i'm sure you knew that) make sure you practice it more than just when your in band, and most of all have fun! enjoy your music, it really makes all the difference from an "eh" performance to a standing ovation performance. Make sure you make every note crisp and clear, toungeing is good but don't abuse it...hope i helped, if only just a little.