A professional (find one through The Pet Professional Guild) can help you train your dog to trust his environment and handler when he is on leash. Dogs can feel trapped by that lifeline. It’s vital that we teach them how we want them to behave when they see other dogs. These behaviors first must be taught in a safe, controlled setting such as a dog-training center.
Now, you may begin allowing your pooch to wear them around the house, increasing the wear time. Keep your pup inside with you, during the beginning of training to help him be successful (training outside can be distracting), and click and reward every time he chooses to be near you while he wears the collar and leash, and remember, consistency is key here. Also click and reward if he looks up at you, this is the foundation to getting his focus-You want his attention to be on you!
This type of training is more effective because it builds a bond of trust and cooperation between animals and humans, the animals (and the humans) actually look forward to training! No one looks forward to punishment, or even the probability of punishment! We all want to be told when we do something right, not belittled, hit or corrected when we do something wrong!