One of the secrets of coaching is that most of it isn't teaching someone what to do; it's teaching them what not to do. There's a reason top players make it look so easy - their strokes are easy, because they are simple and relatively short. There's no wasted motion, and very few actual components to each stroke - and the each part of the stroke naturally leads to the next. A good stroke is symphony of simplicity.
The best strokes are basically the most efficient ways of getting the racket to go from Point A to Point B while creating maximum power. Roughly speaking, correct grip and foot positioning are each one-fourth of the battle. Learning where Point A is - where the racket should backswing to, and the rest of the body's backswing motion - is another one-fourth of the battle. Then letting the shot go naturally and with proper contact is the final one-fourth. If you get the grip, foot positioning, and backswing correct, the rest is natural, though it is often amazing how many weird (and technically poor) incarnations of the stroke players can come up with. Most of these involve flopping the wrist or elbow, or holding back on part of the swing, such as stopping the body rotation so that you stroke mostly with arm, or swinging only with the upper body. Once you have this perfect (or near-perfect) stroke, then it's just a matter of developing the timing to turn it into a weapon of pong destruction.
Done properly, a good stroke is a thing of beauty that channels great power with minimal effort and maximum efficiency. It's the cartographical equivalent of driving from Point A to Point B. A coach's primary job is to get you buckled in properly for this journey (grip and foot positioning), get the backswing right (get you to Point A), and then set you on your way to Point B with no detours, and nothing but constant acceleration through the halfway point (contact) and continuing to Point B.