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.
Determining if this is your dog is a little more complicated, but it is often seen when your dog isn’t very excited (or that there isn’t much of a reason to be excited). This is more than likely to happen when you are in their way or have something that they want. They will usually jump on you and try to push you back more than just jumping up to give you kisses. Often times they will jump on you and try to hold on when you push them away or try to move into them. Sometimes moving into them may elicit a growl because they want to back you off.
Start by teaching your puppy the word NO. Use that word only when she is doing something you do not like. You have to use the word NO in a loud, stern voice that is different from all other ways you communicate with her, so that she knows there is something wrong. You also have to catch her in the act that you don't like, so that it will associate the word NO with the action that she is doing. Be consistent, and follow your verbal command with a light smack or moving her to a time out spot.
To a dog, space and balance are very important. If you take a step backwards or lean out of a jumping dog’s way, it will continue to jump. To a dog, it is overtaking your space, which only pack leaders are allowed to do. When a dog jumps, step into the dog. Picture a sphere around you and are not going to allow anyone or anything to come into your space. When the dog jumps, step into it sideways with your body, shoulder towards the dog. Don't face the dog head-on (you may not have time to turn so don’t worry about it if this is the case). You are not trying to knock the dog down, although this may happen. Don’t be alarmed if you do knock the dog over. Although you don’t want to abuse the dog by knocking it around, this may actually go a long way toward breaking it of the jumping habit as it will create a negative experience. Dogs are incredibly physical creatures and can withstand a lot of physicality without any harm. The odds of inflicting any serious injury are miniscule. You are simply calmly filling up your space with your body, and in return, setting the dog off-balance, which is an uncomfortable feeling for a dog. Lean slightly forward, not backward. Never lean backward, as you will be giving the dog that space. Casually and calmly, keep filling your space, not allowing room for the dog to come in. Remember, your goal is not to knock the dog down, it's just to retain your space.
An anxious or playful pup may leap high quickly and suddenly “poke” at your face with their nose. That can be triggered by leaning over the top of them especially when they’re in a high-arousal situation like a homecoming or around other dogs. It may be a way for stressed pups to relieve their anxiety, so be aware of situations that cause these behaviors. Dogs control each others' movement with their body language. Think how a Border Collie makes sheep move just by getting close. You can stop your pup’s jumps by stepping close to him just before he leaps. Cross your arms and step into the pup’s personal space before he crouches to leap.
In order to perfect the proper greeting routine, your dog needs much more practice than that. You can speed up the training process by leaving through the back door and returning through the front door over and over again. When your friends come over, have them do the same. Each time, ask your dog to sit-stay before opening the door. At first his excitement will make it difficult for him to concentrate but after you've repeated this process 10 times, he will calm down and be able to concentrate. Before asking your dog to sit-stay in this distracting and exciting situation, be sure he has a reliable sit-stay in normal, non-stressful situations. And of course you can always just hold the dog in a sit if need be.
Puppies in human households try to lick the weird, flat, usually bald body part we have instead of a muzzle. When a cute little puppy jumps up to lick face, many people can only say “Awwww!” Hey presto! Jumping up has been rewarded. The puppy’s natural inclination is now a learned behavior. Too bad for the dog when he’s nine months old, bigger and less cute, muddying the pinstripes and knocking Granny to the ground.