Well, everyone has covered what has worked for them. I will tell you what didn't work for us. I started Amos on the front clip halti harness. The idea behind it is that when they jerk or pull, it turns them around to face you...which is not what they want. So, as a concept, it seemed ideal. Shouldn't encourage the pulling but doesn't jerk on the neck. Unfortunately, despite the harness design, the stop-when-they-pull "tree" tactics, the treats he was oblivious to because his surroundings were way more interesting, and the praise I gave when he allowed slack (which he always took as encouragement to pull more?), he was still a puller two years later. Not only was he pulling but he had developed this unhealthy looking awkward diagonal gate to compensate for the front clip harness that allowed him to still get out in front of me but only pull sort of. After the recommendation of my vet and several friends with dogs, I switched to a choke chain last month. (Yes, it makes him look mean. It makes you look mean, but the vet said the correction they receive from it is less than the correction they would receive from their mother as a pup or another dog while playing).
He's not perfect by any means with the new collar, but he's better. He runs straighter which I think will be healthier in the long term for his hips and whatnot. As you can tell, Amos and I have not mastered the loose leash walking/running with ease. He requires a lot of reminding and it's still a work in progress. I'm not sure why it hasn't come together for us as quickly as it has for others, especially considering how regularly we work on it, but I thought there might be useful info here as far as what has not worked for us and just to know that it is not a cake walk for everyone.