One of the biggest things I find is to give them lots of slack, and then start pulling and slowly increase the pressure, as soon as they step forward at all (whether is be 2 steps or only an inch forward with one foot), give them lots of slack, and then repeat it. Try not to pull really hard right away, just start with a little pull and slowly increase, with steady pressure, don't be super jerky, and then just remember to release the pressure as soon as they step forward. Another thing is that he may not like having people around him, which is why he could be really jumpy when you get close behind him. So when I first start halterbreaking (and even after a while), I like to walk around them lots, talk to them, touch them all over. This way he doesn't just bolt when you walk up behind him.