What I did to train Kai is I got a long lead. About 15 feet long and we went to a local park. I would start walking (lead attached to him obviously) if he got ahead of me or went in another direction I would change directions and walk the other way from him.
This will do a few things.
1. Your dog will get a correction and he wont know it came from you. By the time he hits the end of the lead your back is to him when he turns around. So he just got a correction but you didnt say anything and you arent making eye contact when the correction hit so he wont feel punished.
2. Soon he will learn the only safe place to be will be right next to you on your left side. If hes not there he will get corrected.
3. Its very important your timing is dead on. If the dog is next to you even for only a few seconds you need to praise him/her. Any time you get a desired result you praise, if you dont get it you do it over as many times as it takes. And remember your attitude effects your dog as well because they can read your body language like a book. So dont get frustrated.
So don't say a word to the dog or look at them during this process unless you are getting the desired result. If you are walking and you do look down and the dogs there praise him or her. Also another thing, walk fast. This will make the dog focus on you and if you are moving fast and can turn any minute he will be less likely to let his mind wander off whats going on. Stop the problem before it starts if that makes sense.
Remember if the dog gets ahead of you go the opposite way.
You want your dog to look to you for decisions. You never want your dog to make decisions for themselves. You introduce the leash, you introduce the food and take it away, you introduce play time and when playtime ends. That way you are higher in the pack order and the dog knows it.
The next level after that I would cut up some hotdogs in small peices and take him to a crowded place with distractions. Put a peice of the hotdog in your hand and walk and when your dog trots next to you and looks up at you for the treat, praise and reward. Walk ten feet, stop and say sit. If the dog sits he gets a treat if not you do it over until he gets it right. I do this with Kai at the outdoor mall by my house, there are other dogs and lots of distractions. So the hotdogs help, dogs bark at him and he looks and shows no interest because Im walking fast with treats and thats more interesting to him than the Paris Hilton look a likes with the 3 pound dog stuffed in their purses yapping away.
Also remember if the dog does something right get excited and really praise him/her. Pet, scratch and praise, **** act like they won the lotto. It will build his/her confidence and the dog will enjoy training.
I never used a pinch collar on Kai. He has a nice size leather collar about 2 inches wide. I just did what I mentioned above and he walks like a champ.