Keep your heels down and your shoulders back, and use forceful rein pulls to keep the horse from lowering his head. A horse with its head up is unable to buck. Also, keep your legs attached. A rider will frequently attempt to correct bucking by halting the horse. This only encourages more serious behavior because the horse does not want to be stopped. Finally, if all else fails, give him time to calm down. The best way to stop a horse from bucking is with a well-timed rein pull. If you make sure that you don't pull on his mouth or face too hard, then he should drop his head immediately when you release the reins. If you are having trouble stopping your horse from bucking, then someone else can help by giving him a quick rein back behind you. The reason for this is that it forces your horse to turn his head around which makes it harder for him to continue bucking. It's important to remember that horses will usually settle down after a few minutes away from danger. So if you can wait it out then do so, but if you need to end the situation sooner than that, then using one of these methods should do the trick.