Choose what you will practice
Pick one card and study its diagram. Give yourself time to understand the intended path before setting up the balls.
Make a repeatable setup
Refer to the diagram each time you reset the balls. If you use projection, check the calibration first.
Observe before you adjust
Watch what actually happens. Compare it with the intended result and change one part of your approach at a time.
Return to the shot
Repeat the exercise and notice which changes affect the result. Then consider where the same idea could help in real play.