+1 for on the bottom of the jacket.
A more extreme methodology a co-worker showed me was to take your forward hand and put in on you rear shoulder(left hand on your right shoulder if your regular and vice-versa), and your rear hand behind your back.
With this weird positioning of the arms, you feel more stress in the upper body when you use it, thus making yourself very aware when you do. You should only use this as a "self check" and not as a full on riding style.
WARNING!!! if you eat shit backwards, holding your hands behind your back is a fantastic way to dislocated your shoulder. I rider very comfortably with my hands back, but the second I think im losing balance they go right back in front. So just be aware.
Sounds like a good way to get nicely into the back seat, while being well rotated over your heel edge, perfect for a solid downhill catch, eating shit dislocating your shoulder and gaining a tidy concussion