Be Optimistic
David McCullough is quoted as having said, "What matters most in learning is attitude, the attitude of the teacher." He also said, "Attitudes aren't taught, they're caught." If you love what you are doing, the students will catch that attitude. Teaching will be fun for you and learning will be fun for the students.
When I moved to the junior high I was eager to get to know my coworkers. I asked a man who seemed to be an institution at the school what he taught. He answered, "Brats." My initial impression was incorrect. He hadn't been there very long and he left the profession soon after I met him. I really don't know why he left, but I assume it had something to do with his attitude.
Another area where being optimistic is important is in your expectations. You will get what you expect. If you assume that because the students haven't played very long they won't be able to play well, they will prove you right. On the other hand, if you expect them to play well, they will also prove you right. It won't happen by itself. They still have to be taught. But they will rise to your expectations.
I was often told our junior high bands sounded as good or better than the high school bands. I'm sure one reason for that was my high expectations.