What I do is basic from the start, but when I use a direct rein, I lay the opposite rein on the neck so they can get the correlation of the rein on the off side to going the opposite direction. I also use my leg on them up front or on the girth. That's the signal I use for them to move the shoulders only.
Another method is to walk them in a tight circle and they will pivot on their hind foot. That's the point that you stop and praise.
I also want them to tip their nose in the the direction they are turning, so later in the training, if I lay the rein on the left side, and they want to stiffen up or put the nose to the left, I bump the right rein. Same with the opposite side.
I used all of these methods, just in case the horse doesn't quite "get" the other method. It all comes out to the same result
