There are a lot of different methods to teach loose-lead walking (which I distinguish from heeling). For Casper, we've got loose-lead walking on gentle leader, loose-lead walking on flat collar, and heeling on flat collar.
When going for a regular walk, I use the gentle leader on Casper. In the morning, he gets a *very* short loose-lead training walk on the flat collar. The reason I'm doing that is because he puts up with the gentle leader, but hates it. Maybe eventually he can have his regular walks on the flat collar. It will be a while before I teach him to heel on the flat collar. It's at least a couple more intro classes before we get to the Rally class where we need to do an official heel. And, for Casper, heeling will always be, I think, a two-minute exercise in the obedience ring. He's still young, we'll see.
I just finished reading a book, Bonding with Your Dog. The leash walking section starts with "Ah, leash walking. The most challenging, frustrating, potentially annoying behavior in the basic obedience handbook. ... The challenge is that it isn't easy to untrain a committed puller." And "It's unfortunate, but leash pulling has a fairly high relapse rate after training." Well, finally someone admits it. I have tried several different leash training methods. And given each of them a solid, good try. We don't have perfect walking, but we've managed to keep Casper from being a committed puller. At least this week. Now that most of the bunnies have gone into hibernation. Now he's faking me out on the bunnies. He used to take off after them the second he saw/smelled them. So we'd be a good distance away working on sit/stay. Now he trots nicely as close as he can get (no tip off to me), then whoosh! he's off. Somehow that seems like an improvement.
I did try the turn-around method. But I got dizzy.
The method in "Click Your Way to Rally Obedience" worked for a long time for us when I was walking Casper on a Wonder Walker. I tied the leash to my waist. (Might not work for a committed puller.) Then I had one hand for the clicker and one hand for the treat. And it also prevented me from using the leash for corrections. On the flat collar, I'm using the method from the Bonding book, which is basically that when the leash gets tight, you stop, wait for the dog to turn back and look at you, then click and treat at your side. The idea is for the dog to turn around as soon as he feels pressure. So far so good, but we only go around the block. And there is still work to do so that he figures out not to just run to the end of the leash, then pull, turn around, and get the treat.