Ask about 504 and T-tess stuff.. Wish I knew more about that stuff....accommodations....gradebook...
Stuff that you think band people don't need/have to do^^^^^^
Have a really good relationship with your mentor. They will be giving you recommendations for your future job!
Also, get comfortable with other instruments. Stray away from your main so you can soak up tips to help you teach other instruments. I am a trumpet main teaching beginner Saxophone, Flute, Clarinet and Percussion.
Lastly, ASK QUESTIONS.... Ask WHY they do certain things.