When trying to stop dogs from jumping up, most people try to correct the behavior by using punishment. With positive reinforcement, however, you want to focus on what you want your dog to do rather than what you want them not to do. So, when teaching your dog not to jump up, you want to reward your dog for having all four feet on the floor.
In order to make the Four on the Floor behavior work, you will need to do the following things: 1) Teach your dog that keeping all four feet on the floor will bring them rewards, 2) Reward your dog for not jumping up and 3) Ignore him when he does jump up.
Set your dog up for success by having treats ready in your hand before greeting him at the door. When he approaches you, set the treat on the floor by you before he jumps up. Continue placing treats on the floor as long as he keeps his four feet on the floor. The rewards he receives when he has Four on the Floor will cause him to want to repeat that behavior.
If your dog does jump up, immediately withdraw all your attention, including saying anything or even looking at your dog. Turn your back, and cross your arms so your hands are nowhere near him. A common and automatic reaction to a dog jumping up is to say “No!” however any attention will cause the dog to jump up again. When he returns to Four on the Floor, you can give your dog attention again. Then step back, and if he keeps all four paws on the floor you can then reward him with a treat.
You will also need to work with others that come in contact with your dog. Ask them to only give him attention when there are Four on the Floor, and to remove their attention when he jumps. This will teach your dog that jumping up never works to get attention or rewards, whether on you or on others, and that the Four on the Floor behavior does.