CENTRED RIDING by Sally Swift

A great book using interesting imagery, especially good for the seat!

"Don't block your downward weight by pinching with your knees or any part of your legs. Let your legs rest softly against the horse's sides. Use your hip and knee joints freely so you can feel the full up and down motion of the rising trot."

Re jumping: "You will need to have a tighter seat than when you're on the flat because of the increased and, at times, unexpected activity of the horse; but at no point must it be locked, or else you will not be fluid. Shorten your stirrups until they hang slightly above your anklebone. Push your pelvis farther back in the saddle than you did for flatwork."

Re transitions: "The key to success lies in not jamming your seat bones onto the horse's back, but allowing him to round his back under your light, but following seat."