First, use Pro One to aim. The donut about 3" in front of the CB helps to see how straight your stroke is. The goal is to hit the shot, the primary goal is to have a perfectly straight stroke. If your aim perfect and your stroke is straight, you should be able to hit a follow shot into the pocket or draw the CB back to the tip of your cue. Using a measles ball also helps verify that your hitting dead on CCB.
Really helps diagnose a problem if you're off a bit. It helped me recently figure out I was tending to place my bridge off line to the left very slightly.