Having clear expectations and setting reachable goals will help you enjoy playing ultimate better. Not only will it help define your role on the team but it will help you become a better player, it will help you enjoy practices and games more than you did before and it will help you be more effective when you practice.
Good thoughts Rob, putting deliberate thought into your practicing, establishing personal goals, and understanding your role within a team are all aspects of the game that many players don't put enough energy into.