You're on to the most important part, practice and repetition. The best way to learn one particular disc is to pick up multiples of the same mold, plastic and weight you like so when you go to do field work you can get in more reps between disc shagging. You will probably find that the extras are not as redundant as you thought since you may lose one from time to time, and you may also end up wishing to carry multiples of the same disc in various stages of wear to vary the flight lines slightly.
Another way to maximize your practice sessions would be to go out with Zippyboy, or whoever, and throw drives back across the field at each other shagging for the other guy. To make it more interesting, try and throw farther than the other guy and back him up.