Answer: First of all, it would be extremely hard for me to recommend a mouthpiece for someone I don't know. If you are in elementary school, I'd generally recommend starting off with a Vincent Bach 7C mouthpiece. If you're in junior high or high school, it really depends on your progress as a student. If you feel you are outgrowing your old mouthpiece, go to your local store, ask for 3 each of 5C and a 3C Vincent Bach mouthpieces. This is crucial, because no mouthpiece is exactly the same, and you should be able to tell which is better by playing scales or simple songs on each. The mouthpiece should feel comfortable, sound good, and it should not compromise things like range (low as well as high), accuracy, attack, and stamina. CHOOSE WISELY!! For kicks, I play on a 1 1/2 C Bach on my Bb, a 1 1/2 Bach with a 24 backbore on my C and D, a 7EW (wide) cornet mouthpiece on my picc, and a 3C on my Eb Cornet. Good luck choosing!
-Joe
Joe@TrumpetBoredom.com