You should have lots of treats ready for this training technique – it is essential to reward your dog IMMEDIATELY he exhibits the correct behaviour. He will not remember what he's just done if you leave it too long, by searching in your pocket or a bag, so you should have the treat already in your hand, anticipating his obedience. When he masters the command, you should give him his favourite treat straight away and praise him.
This exercise is best carried out with two people. (If this isn't possible, a long training leash can be used, along with the stay command.) One person should hold the dog's collar, the other should show him and let him sniff his treat. Then close your hand over the treat and back away from your dog while your companion holds his collar. If your dog already knows how to sit and stay (and he should do!) then use this command while you back away from him to about ten feet distance. Now stop and call your dog's name followed by the word “come”. You must be consistent, always use the same word in the same tone of voice. Later, if you want friends or family to use your dog's commands, you must teach them how to say them and use them correctly. Inconsistency will confuse your dog and undermine your training techniques.
Once you have called your dog's name and the word “come”, your companion should release the collar and your dog will almost certainly return to you. Give him his treat and praise him enthusiastically. Repeat the exercise many times, increasing the distance between you and your dog and even going out of his line of sight. He will soon have learned the exercise and associate “come” with a nice treat and praise.
The next part of the training is to take your dog outside to a quiet location. Your companion should hold your dog on it's leash and run over to you with the dog when you give the “come” command. Once it is clear that the dog is responding well to the command and responding to the positive reinforcement of the treat, you can try the command with the dog off the leash in a safe environment.
Remember to always use positive reinforcement for this exercise – don't call your dog to you to tell him off or to do something he dislikes, like putting his leash back on. If you want to get him back on the leash, you can trick him by calling him to you, playing a little game where he stays close to you, then putting his leash on, so he doesn't associate the command with something negative. Some dogs don't see the leash as negative and therefore you can just call him as normal and give him a treat or praise him.
As with all training exercises, the key to success is repetition, patience, consistency and positive association. Your dog will be a happier, healthier, safer dog for accomplishing this simple task in a variety of environments with differing degrees of distraction until it is an automatic response.
