Teaching Your Horse to Neck Rein
The tails of the reins should fall on the same side of the neck as the hand you’re using to hold the reins. It’s traditional to hold the reins in your left hand, leaving your right hand for roping cattle, but riders are free to use the hand they prefer.
Training
Your horse needs to figure out that he will get freedom, or release the rein will go slack on his neck each time he moves his neck and head away from the pressure of the rein. This is how you will deliver a “yes” to your horse for a correct response. This is the part that takes time. Around a circle, for instance, you may repeat the cycle of applying neck pressure and then softening the instant the horse moves his neck to the inside many different times for multiple “mini turns.”
Avoid neck reining so hard that your horse counter bends his head to the outside. Use the direct rein as a help in the initial stages to guide the horse’s nose away from outside rein pressure; reach down with your free hand to use the direct rein (left rein to turn the nose left) as you maintain pressure on the neck with your rein hand. As soon as he turns his neck and head away from the pressure, release both the direct and neck rein.
As with anything, repetition is the key. Avoid moving on to the trot until your horse is steering reliably at the walk. A horse with a good handle, who is light and responsive to the neck rein’s slightest pressure, is a joy to ride.