The best way to learn has been stated - If you know exactly how each joint's action affects the ragdoll, you'll be able to figure out how to create moves and combinations of settings to get where you wanna be.
For example, bending the lumbar to left, extending both glutes, contracting the right hip and extending the left hip will get somewhat of an odd kick going on. But then, don't think of that in itself as a combination of moves, think of each action seperately, otherwise you'll keep relying on the same thing.
Its hard to explain, and hard to grasp, really. I suppose a good idea would be to start out only controlling parts of the body at once to, say, do a punch without moving your legs, or curl into a ball. One thing you could try is to figure out what the body joints do over anything, and how they affect the limbs.
I guess its just patience needed to learn the game. This is different from most games - Its hard to learn, and harder to master. Time really is the best teacher though.