some of this stuff has already been mentioned. but here's my own advice:
- remember to follow through
- practice a lot. being consistant in every part of the throw is very important. this includes where you start walking from and how many steps you take. (walk in a straight line too!)
- clean your ball regularly
- any lane on any day can have different amounts of grease on it and in different spots too. learn to read the lane and adjust your throw accordingly.