Introduce the puppy to the collar or harness and leash. Start out by letting him get used to wearing a collar or harness and a leash. Let him wear them for short periods at a time in the house while you are playing with him and giving him treats. The puppy should love collar-and-leash time because it represents food and fun.
Teach a cue. Introduce your puppy to a sound cue that means, “food is coming.” Some people like to click and treat, some people use a word like “yes,” and some people cluck their tongue. Whichever you use, the method is the same: In a quiet, distraction-free area, with the puppy on a leash and collar, make the sound. The second your puppy turns toward you and/or looks at you, reward him with a treat. After a few repetitions, you’ll notice your puppy not only looking at you, but also coming over to you for the treat.
Make the puppy come to you. While he’s on his way to you, still wearing the leash and collar, back up a few paces and then reward him when he gets to you. Continue the progression until your puppy, upon hearing the cue noise, comes to you and walks with you a few paces. Remember that puppies have a short attention span, so keep your sessions short, and end them when your puppy is still eager to do more, not when he’s mentally exhausted.
Practice inside. Now that your puppy understands how to come to you, practice walking a few steps in a room with little distraction. Feeling and seeing the leash around him will be enough of a challenge. Offer treats and praise as your puppy gets used to coming to you, as described above, with a leash on.
Take it outside. Finally, you’re ready to test your puppy’s skills in the Great Outdoors. There will be new challenges with this step because all the sounds, smells, and sights your puppy encounters will be intriguing and new to him. Be patient and keep the first walks short. While you’re on a walk, if your puppy looks as if he’s about to lunge toward something or is about to get distracted (you’ll notice this because you will keep your eyes on him at all times), make your cue sound and move a few steps away. Then reward him with a treat for following you.
Leash-Training Troubleshooting. Even though your puppy may be learning to walk on a leash very nicely, you’re likely to run into some issues as he gets older, goes new places, and experiences new distractions. You’ll want to teach him loose-leash walking, because it’s much more pleasant for you both.
If your pup pulls: If your dog starts pulling in the other direction, turn yourself into “a tree.” Stand very still and refuse to move until your dog comes back to you. Do not yank or jerk the leash, and do not drag your dog along with you. Front-hook harnesses and head halters are alternative training tools designed for dogs that tend to pull.
If your pup lunges: If your dog is going after something while on a walk — another dog, a car, a skateboarder, for example, be proactive. Try to redirect his attention with a treat before he has a chance to lunge, and increase the space between your dog and the target. Stay alert and be prepared before the target of his frustration gets too close. This type of behaviour may be more common in herding breeds, but any dog can be startled by something he’s not used to or finds exciting.
If your pup barks: Some dogs have the habit of barking at other dogs while on a walk. Often times, this behaviour comes as a result of lack of exercise. Make sure your dog gets the proper amount of mental and physical stimulation for his age and breed. If this is still a problem, use the same process as you would if your dog is lunging, as described above — create distance and offer treats before he starts to bark, so every time he sees a dog he gets used to turning his attention to you.
Gradually you’ll reduce the number of treats and the amount of troubleshooting that your puppy needs during a walk, but it’s a good idea to keep some on hand at all times so you can randomly reinforce good leash-walking behaviour. Positive reinforcement like rewarding your puppy with a treat every time they do something right works very well during training.
**Information courtesy of https://www.akc.org/expert-advice/training/teach-puppy-walk-leash/