There are a number of different reasons why your dog will pull on the leash. Some dogs are so happy to go for a walk that they are out of control, and are anxious to move about. Other dogs see themselves as being the leader, and will move forward with force because they feel that they are moving ahead of the pack. If you r dog is very happy about going out, it may help to give them some time to calm down. You can stand still with the dog for a few minutes until they become more relaxed.
If the dog feels that it is the leader, this is a sign that you should begin training him. The owner has to show the dog that they are the leader. When you don't have this understanding with your dog, it will be impossible to train them properly. If your dog shows signs of control, it is best to go back to simple obedience training. If you don't have the time to train the dog yourself, it may be best to send them to a dog training school.
The instructor can train you as well as your dog, and they can show you how to keep the dog from trying to be the leader. Skilled instructors should always work with both you and your dog. The first step in getting the dog not to pull on the leash is to get it to accept the collar. If the dog is moving around a lot while you are trying to put on the collar, this is a sign that your dog will pull against the leash. Start by commanding your dog to sit or stay while you put on the collar. If the dog gets up after you've put on the collar, make him sit back down quickly.
You should only walk the dog after it sits down calmly and allows you to put on the collar and leash. Once the collar is on, don't allow the dog to jump up and rush ahead towards the door. Gently pull back on the leash. Make him sit back down again, and repeat the process until he gets the message.