Homecomings and departures are a prime time for jumping up because puppies want to greet you or stop you from leaving. Turning your back on some of these dogs revs them up even more, so instead, try ignoring the bad behavior. “Ignore” means you make no eye contact, say nothing and stand still like a zombie offering no reaction to silly puppy behavior.
Dogs like and need consistency, so if you are not allowing your dog to jump on you, everyone in the family and everyone who greets the dog must do the same. You, as an owner, must make sure this happens. It will only confuse a dog if you allow them to jump on some people who say they do not mind, and tell him not to jump on others. Once you decide you do not wish your dog to jump on people you must apply this to everyone at all times unless you give the dog a command to jump. A dog should never jump on a human of its own free will.
Other commands can be substituted for ‘sit’ if you prefer, such as ‘stay’ or ‘down.’ However, if your dog simply gets too excited to execute these commands properly (as is often the case, especially with puppies) try diverting their attention elsewhere. Ask them to go find their ball, or a favorite toy, as a way to distract them and expend some energy. And, as always, reward the good behavior with praise.
A relatively new invention that will definitely solve this problem is the no jump harness. It works by restricting the movement of the dog’s hind legs so that it can’t jump at all. This should not be a permanent solution but rather something that can be effectively used during training. It should not only stop them from jumping chain link fences, but also from jumping on people and furniture.
When a dog jumps on a human of its own free will, it is not "greeting" the human, it is asserting its dominance over the human; it is the dog communicating that it is alpha and/or wishes to own/control the human. A subordinate would never dream of running over and jumping on the alpha dog of the pack. Space is respect and lower members of the pack respect the higher members. If your dog jumps on humans, it does not respect them. Note: when a young puppy jumps on humans it is sometimes its attempt to reach one's face. Puppies need to be taught not to jump up on humans as this behavior will manifest into other meanings as the puppy grows up into an adult dog.