I have the same problem, and its taken me a while in figuring out how to do it right. Even then, I still pick up a few fouls a game, but my steals have increased considerably. First thing, whatever you do, do NOT attempt to steal multiple times in a few seconds. Its a almost a guarantee to pick up an 'intentional foul.' Other than that, as mauriocioq stated, you have to time it at the right moment, and the ball placement and trajectory also come into play. Its part skill, part timing, and part luck.