Stop walking and turn as soon as you feel pressure on the leash, or your dog will learn that pulling «works» for getting him what he wants. (woofwhiskers.com)
Let your pup drag the leash, then let him lead you, and finally put gentle pressure on the leash to lead him. (countrysideveterinary.net)
If the dog does forge ahead, steady pressure on the leash will turn him back towards you and prevent that arm - out - of - the - socket dash down the road. (canismajor.com)