Course management is going to be what seperates the good from the bad in high school golf. When I played many moons ago there were allot players on each of the teams I played against who could shoot low numbers when they were playing well, but very few that could do it when things were not. You are going to have bad days, bad lies, bad weather. You need to learn how to make the best shot given the situation you find yourself in. I think the best way to acomplish this is to practice on the course and create situation for yourself on the practice range and try to duplicate trouble shots.
My advise would be set yourself up and scheduel of range, short game and on course practice. I would spend the least amount of time on the couse actually trying to shoot a number.