Communication- Make sure you(the pitcher) are communicating with your coaches at school and if you are working with a private instructor, you are communicating with your private instructor. If your coaches at school don't know what you are doing on your own or with a private instructor, or if your private instructor does not know what your doing with your coaches at their workouts, over-training and over-throwing becomes an issue real quick. By communicating you will have a better chance to train smart and not hurt yourself or your chances to make a team.
As a slight side note: We have our pitchers take their "charts" from HS practice to their private instructor and keep track of everything.