The nose should be kept behind the belly button
Both the reins should not be pulled at once
Proper use of one rein
One rein is meant for an emergency and not for everyday use. When something happens and the horse needs to be stopped in an emergency, one rein should be pulled; it helps the horse release the hindquarters and relax its body, and let it follow its rider's instructions.
Getting off is the only option if the horse can't be controlled
A rider should never forcefully ride on a horse if the situation is not in favour of the rider. The tension of the rider never lets the horse calm but makes it worse. Thus, he needs to get off then and there.