
I used the stop-start method for my two when they were pups - if they pulled, I stopped and said "no" sternly, waited till they moved towards me (got slack on the lead) then carried on. Depending on the pup whatever method you use can take a lot of patience - I used the same method on both mine, and my girl walks very nicely without pulling, but my boy still pulls so is on a halti harness. It was my fault, really - I didn't follow the golden rule of dog training: Be consistent! However you do it, be patient - no shouting or physical corrections, aside from maneuvering them back into place if need be (I used to gently pull my boy back and say "back" until he started walking backwards into place on his own), negative actions like these tend to be counterproductive.
Regardless of the method, don't let them get away with pulling *at all* - pups learn rediculously fast what they can and can't get away with, and pulling can be a b**ch to sort out if they think they can get away with it, once they're older. It's the mistake I made, and my arm is paying for it :)