Hi there, I've had good luck with just doing circles. This will help the horse give to the bit better. Just sit on his back and walk him in circles using only the inside rein. Don't put any pressure on the outside rein. As he's walking, tighten the inside rein until he keeps slack in it. It just makes their mouths softer. I usually do it a few times each way as a warmup for my horses and to keep their mouths soft.
Do not go where the path may lead-Go instead where there is no path and leave a dusty trail.