When I give lessons that I preach and preach - Proper form and stroke, over and over, and over .... and If they get testy, I just make them start all over again like a drill sargeant until they finally start catching on.
Proper form and stroke is like the planning phase of a project, it allows everything else to follow to go much easier than it would otherwise.
And we all know, that with proper planning, you are better prepared to
take other things on.
Sun Tzu from his book, The Art of War states:
If you know yourself, you will win some of your battles, if you know your
opponent, you will win about half of your battles, if you know yourself and
your opponent, you will win most of your battles.
That statement can apply appropriately to Pool as well. If you truly know how good you are and your skill, you can win some of your matches, if you know
your opponent, you can evaluate his skill level, weaknesses, plus have a good
idea of how much a spot should be for a fair game. If you know both, you can capitalize on your strengths, exploit your opponents weaknesses, know how you should match up, and win most of your matches.
Every real good pool player is real good at evaluating skill levels of different
players, that's why they win most of the time.