walk nicely on a leash from the very beginning. you don't have to expect him to walk perfectly on heel, but he should be able to stay with you without pulling, and he should make all the starts, stops, and turns that you do. if you use a jewel-link training collar (don't think of it as a choke collar -- that's not how you should use it), any time the dog begins to pull, give a quick snap and release on the leash and tell him, "heel" or "slow" (whichever word you choose, be consistent). when he backs off, praise him.
another alternative is a head collar -- a device similar 