Instead of "pulling" the rein forcing the horse's head around, you want the horse to "give" instead of just following your hand. I would say put just enough tension for your horse to feel it in the rein, and then rest it next to the horn on the saddle to create kind of a wall. As long as the horse pulls the other direction, doesn't do anything, etc, etc, leave your hand there and keep the medium tension in the reins. As soon as you feel the horse "give", turn its head towards you so the rein has slack, or you feel a release of tension in the rein, release. Kind of the same process as others said, but wait for the horse to give BY ITSELF, instead of YOU making the horse give by pulling the rein.
Hope this helps, and good luck!!