Now you are ready to try the leash. The first day allow the puppy to walk in any direction and follow him, just correcting any excessive pulling, saying “NO” and turning in the opposite direction to let him know that he won't be able to go anywhere if he pulls too much.
After a couple of days start pulling on your puppy saying, “LET‘S GO” and gain his attention. Don't let him smell the ground and make him follow you.
They learn faster if you are enthusiastic and praise him every time he accomplishes a command. Puppies love high pitched reinforcement.