Alot of practice doing turn arounds slowly. This is a movement alot of people get sloppy because they get too stupid about trying to pull the horse around too hard in front which forces the hind end to step out and you loose your pivot point. You should ask the forehand to start walking around a step at a time, when you feel that you are loosing your pivot point, which is when you feel the horse lean to the outside, that is when you should halt, or half halt on the reins, apply outside leg to re-align the horse, then ask for another step. When you do this too fast at first you loose the control to balance the horse correctly. So just remember, if you can't do the turn-around correctly slow, no way to do it fast correctly. However, current trends for the last several years now in reining is to forget the correctness of the spin and just do what I call is a fast turn-around while loosing the pivot point. Reining is a lot more like western pleasure showing now a days.