Your son should be ready to play his absolute best. This might sound redundant but if he's a pitcher, he shouldn't be pitching any games this weekend. If he's a position player, practice fielding & do BP all weekend. If you have to travel to the tryouts make sure he gets enough rest the night before and/or isn't stiff from riding in the car for hours just before the tryouts start. He needs to be at his very best, trust me, been there done that.