The phrase 'positive reinforcement' can be broken down to mean adding a reward to a behavior in order to increase the occurrence of that behavior. The reward given must be something that your dog views as special such as a treat, affection, or a favorite toy. This technique can be used to shape a variety of behaviors.
The Importance of Timing
Good timing in training is crucial. Dogs live in the moment, and even a few second's delay between the behavior and receiving the reward can make the training ineffective. Dogs are engaging in many behaviors at any given time, and in the few extra seconds taken to give them the reward they may have licked their lips, yawned or just made a simple movement, but any of these can be mistaken for the rewarded behavior. The reward must be given immediately following the desired behavior.
Teaching a dog to sit can be easily done by getting him to follow a treat. Begin by putting a small piece of treat in front of your dog's nose and then bring it slowly up and over the dog's head. In an effort to follow the treat, the dog should tilt his head back resulting in his hind end hitting the ground. If necessary, you can apply some pressure to the hind end to encourage him to sit. Reward him immediately when he is in the sitting position.
Practice this a few times before adding the word 'sit'. The verbal command is not effective until he has a movement to associate the word with.
The same technique can be used to teach your dog to lie down. When he are in the sitting position, start by putting a treat in front of his nose and then bringing it down between his front paws. In order to follow the treat, he should lie down on the floor. This may not work with every dog. If necessary, gently push down on his back as you lure him with the treat, or gently lift up the front paws and place them in the down position. Repeat this a few times before adding the word 'down'. Give him the reward immediately when he is in position.
The command 'come' is most effectively learned by using positive reinforcement. This can be a life saving command if the dog were ever to get loose, so it is important to never call your dog to you to scold, punish, or deliver anything he views as negative. If this is necessary, go to him instead. This will make sure that he never views coming to you as anything but a positive experience.
Practice calling your dog to you by saying the command 'come' and giving him his reward as soon as he gets to you. It may be helpful at first to squat down to his level or make fun sounds, such as whistling.
Fading the Reward
Once your dog is responding well to a command, it will not be necessary to give a reward every time. In your training sessions start giving the reward only every few times he does a certain behavior. This will keep him guessing and ensure that he will be able to obey a command even if you do not have a reward in hand.