Any conselhos you can give to another actor without too much experience?

I am in middle school and I have already been in 3 plays and I have never had a lead role but now all of the best actors are in high school so now I figured that I now have my best chance of getting a supporting role(for a boy there aren't much lead/supporting roles in this play)in my middle school play.I am very determined to get this part!(help!)