The reins on a horse--the straps extending from the bit in the horse's mouth to the base of her neck--act as the steering wheel and brakes for the rider. Learning to hold them properly not only gives you more control, but also helps the horse to have a pleasant, comfortable experience during a ride.
Grasp one rein in each hand as soon as you're in the saddle. If you're a beginner, ask someone with riding experience to hold your horse steady while you get your hands ready. The reins are your biggest form of communication with your horse and holding them properly is essential. Adjusting them so that they don't have contact with the horse's mouth, position the reins so that the strap on the left side of the horse's neck comes up into your left palm by passing through the space between your little finger and your ring finger. It should pass out of your palm through the space between your pointer finger and thumb. Repeat with the rein in your right hand.
Close your fingers so that you have a firm grip on the reins. Press your thumbs down on the top of each rein so that they lie flat against your index fingers and point toward the horse's neck. Make sure both thumbs are pointing toward the horse's ears and your palms and curled fingers are facing each other. Allow the ends of the reins to hang down on the side of the horse's neck. Most experienced riders follow tradition and drape theirs over the horse's left side, but it's OK to allow them to fall to the right. Hold your hands just in front of the saddle, about six inches apart and five inches above the horse's neck.
Take up the slack in the reins gently so that you have light, steady contact with the horse's mouth. This is called "shortening" the reins. If, when riding, you need to shorten the reins, take both in one hand. Slide the other hand down the rein on the same side. Close your grip around that rein, then switch, taking the other rein into that hand and holding it, while the other hand slides down. When your reins are the same length, close your fingers firmly around them and double-check your hand positions. If you took hold too tightly on the horse's mouth and he seems uncomfortable or agitated, gently lengthen the reins by opening your fingers slightly and allowing the straps to slip through slowly. Close your fingers firmly again when the reins reach the right length.
Your hands should feel slight, steady tension on the reins, which is called your "contact." When you increase or decrease the amount of contact you have with the horse's mouth, he'll take that as a signal that he's supposed to do something different. Try to keep your hands steady and moving only slightly forward and back with the natural nodding of his head as he moves forward. Your reins can be used to stop or slow the horse by pulling back gently. As he responds and slows to the speed you want, relax your contact, a signal to him that he responded correctly. But don't "throw away" your reins, as riders say. Keep them short enough so that you can signal the horse when you need to turn, slow or stop again. Your reins also can be used to steer. When you want the horse to move left, pull back gently on the left rein and give a little with the right rein. Try to keep your elbows close to your body. To turn right, pull back gently on the right rein and give slightly with the left. When you want the horse to go straight again, move your hands back to the position just in front of the saddle and hold them with equal tension.
Holding the reins improperly will make it harder for you to control the horse. Common mistakes include holding the reins with upturned palms, downturned palms or hands curled in. It's also a mistake to clutch the reins tightly or hold them loosely, with open fingers. A firm, relaxed grip is ideal. Snatching at the reins with unsteady pulling and jerking might irritate the horse so much that he'll try to get you off in the fastest manner possible. Dropping the reins while riding leaves you no way to control the horse--a dangerous situation for you and for him. Keep a firm grip on them until you dismount.