CoachRobert,
Your son's select coach gave you a great list. To expand on the attentive tip, make sure your son knows that means no talking when the coach is talking and to always look the coach in the eyes when he addresses you and say yes sir or no sir in a voice loud enough and firm enough to show confidence.
In addition the 1st week a freshmen enters school he needs to start trying to make an impression on the coach by:
a) Getting good grades
b) Show all teachers respect and don't get into trouble.
c) Attend all voluntary workouts possiblet hat may take place in the fall and winter. This includes weight training, conditioning etc.
Good luck to your son and be sure to tell us how the tryouts turn out.