i started throwing lefty a year or so a go to compensate for my lack of a forehand shot. as far as drives, i concentrated on my footwork and i felt that helped me alot, lots of reps trying to be consistent with my footwork.. also i put an orange cone 30' in front of me and i tried to make sure i was releasing at the same time so i would attempt to have the disc fly directly over the cone, helped me with accuracy.
i have the luxury of getting lots of reps in because i have a dog that will bring them back to me so i can get 50 throws in about 20 minutes. practice, practice.