When I practiced ground tying, I always worked on dirt, with as little potential for distraction as possible. You need to be able to have "success" so that you can reward them for their good behavior.
I stand the horse up, and always depart by turning myself around and beginning the walk around facing the horses rear. Didn't want to confuse them that they should follow. If they move a foot, or drop their heads, I return quietly (quick too, but don't want to startle them) and set them up again, or lift the head, repeat the tug on the lead, or voice command "stand" and leave again. If they can only "hold" it for 5 seconds or a couple steps initially, then you know you'd better be ready to return to them at 4 seconds so you have an opportunity to praise them. Gradually extend the time, so that you can make a complete circle around them. Kind of like the Stand Stay in the dog obedience ring, there's no really "good" correction you can do for this exercise except repitition, and the opportunity to reward.