More on the concept of simple (see this post if you don't know what I'm talking about).
One thing I've struggled with in my riding is a tendency to block the horse's motion, either by bracing - with hand, leg or seat - or by focussing on the wrong things.
I find it very helpful to think of bending, not as changing the orientation of the horse's neck or body - thinking this way often leads directly to blocking the motion - but as influencing/directing the horse's leg (or legs). Bend then results, without blocking or bracing, from the feet upwards, rather than from the body downwards. The resulting feel is much better - the power comes up from the feet.