You can practice getting the right hit on the break by racking just three balls in a triangle on the head spot. Make sure those three balls are frozen, and "racked" straight and with the head ball right on the spot. Now play the break just as you normally would. With just three balls, it is very easy to observe exactly what direction the corner ball goes towards your own pocket. If it misses to the foot rail side, then you are hitting too much of the head ball. If it misses to the long rail side, then you are not hitting enough of the head ball. If you are starting to more frequently get it close to your own hole, then rack all fifteen and see if things are going better with your break.