This drill will improve the follow-through and the precission in hitting the cue ball on its central axis.
We shall hit the cue ball on its lower central part, with lots of follow-through.
The cue ball should remain on the spot where the object ball used to be, and the object ball should rebound off the cushion to hit the cue ball again.
You should practice this drill in series of 10, writing down how many times you did achieve a succesful result.
If the previous drill is to simple for you, you could try a more demanding version of it, hitting the cue ball stronger (stilll aiming to the full object ball, and trying to achieve a straight rebound).