Put the collar and leash on your dog at home while you’re both relaxed and calm. Let the dog get used to the feel of the collar and leash at home before going out. Give him some treats or his dinner while he’s wearing it so he associates it with good things. Do this few times over two or three days. Then take the leash and follow your dog around the house, getting him used to the feel of the leash being held and of you walking beside him. Now try this exercise in the garden, while it’s quiet and free from distractions, letting your dog pull the leash around, and then occasionally pick it up and follow him. All of this will make your dog familiarized with the sensation of having the leash and collar on. Now hold the leash and encourage your dog to walk to your left by enticing him with a treat in your left hand. Praise him and give him a treat when he walks well besides you. As soon as he tries to pull on the leash, turn clockwise and walk in a different direction. Repeat this until your dog learns that he must watch you and follow your direction, and that he will be praised and receive a treat when he does it right. Never chastise your dog for getting it wrong, just praise the correct behavior.
After a good leash training session, why not treat your dog with a good dog grooming session. He’ll love have having his coat brushed and it’s a very good way to enforce your position as the leader of the pack.