Keep your free throw routine simple. Try this classic routine: take three dribbles, bend your knees, look at the hoop, breath out on your way up to shoot, and hold your follow through. If you choose a different free throw method, remember to use the same method on every free throw. Even during practice. The more you do it in practice, the more comfortable it will be in the game.
Listen to what MJ says:
Or check out these odd routines (not recommended):
Or do what Jackie Moon does (just kidding don't do this):