Be quiet and unassuming. Be absolutely "professional" in your attitude and demeanor - always being prepared to the best of your ability and on time. Thank your section mates for a good performance. Only offer advice when asked and then be as succinct as possible. Ask your folks about private lessons. The rest will come.
By definition at my high school, freshmen did not play in the "varsity" concert band with sophomores, juniors and seniors, although we all marched together for half time field shows and parades. But...I was fortunate to be in a similar position in choir as a freshman. Unfortunately, I did not always heed the above words, and as a consequence I was hazed severely by upperclassmen.