Our BC, Brie, just turned seven months old and I finally have found time to go out and work on heeling with her. I think most of my procrastination came from a bit of dread I was feeling after reading about how difficult it can be to teach your dog to heel. I should have know better, especially after she has picked up everything else so quickly. I was inspired, after reading numerous training books and researching heeling in particular, by the Monks of New Skete and the Art of Raising a Puppy.
Brie has been a puller from the beginning, and we curbed it a bit, but didn't teach her to heel. Using the techniques discussed in that book, and taking her out to a large field, she learned it in five minutes and continued to do an almost perfect heel for the next ten, including "gliding" into the sit down as I stopped. I use what is called a prong collar, which, from what I've read and been told, is one of the safest AND most effective training tools for teaching your dog leash manners. However, I wouldn't recommend it for very sensitive dogs. Instead of choking your dog or jerking her little trachea like choke chains do, when used properly it pinches the skin but doesn't do any damage. Part of the teaching technique called for a "pop" of the leash with a "no" at the same time.
They don't use treats in their training, but we will periodically use them with Brie (to keep her guessing I suppose, it's working). I like the idea of holding the treat in the mouth so the dog is looking at you.