I'm going to be in MB next year for highschool.I'll get the music in about 3 weeks.Is there anything I should start practicing now.I'm going to some camp called Smith Wallbridge too.

play scales while walking!

I was about to suggest practice holding the instrument up for long periods of time, then i remembered- clarinet, not an issue

but do try standing ridiculously still. if your band is anything like mine, that's pretty important.

uhhhh, that's all i've got. suddenly it seems like a really long time since i marched clarinet

also, make sure that when you practice your marching, you're gliding (as mentioned above). You don't want to bounce, basically. and, i don't know how many bands do this, but when our band backward marches, we stay on our toes. is this the general rule?

also, practice your sliding. sliding is when you're marching, your body is turned (and i'm not sure about this, but i'm just trying to give you a general idea) at a 45 degree angle, and your neck at a 90 degree angle towards the press box (you'll see what i mean later on).

umm, two years in marching band so far, and i think this is the best advice i can give.