You realize that the ball should take a downward trajectory, so add to that a lower target; for example try to hit home plate, then the catchers toes, then his knees and shoulders. Try to feel what your body/arm is doing each time, with no batter of course. Then work downward and make adjustments accordingly. Sometimes a simple solution for a high pitch is to pinch the ball. Trying to adjust a release point one-half inch is a difficult task. I am always curious how one differentiates between aiming and a normal pitching motion. As young pitchers learn the mechanics of pitching at some point they have to try and let one fly so they can learn how to control it. So, overthrowing is not always a bad habit. Aiming needs to be demonstrated or re-defined.