Yeah, jumping is always an issue. I allow it with Renji because I like his pushy attitude (sometimes
) but that also means he does jump on guests! Well, this is a dog household...
I find that Renji jumps a LOT more if things are excited and uncontrolled. If I first make sure his energy has been burned out through physical and MENTAL exercise (training), then that's half the battle because a tired dog has less energy to devote to being a kangaroo. Next, the guests must come in *calmly* and IGNORE the dog! Greet me first, let's get everyone settled down, forget the furry four-legger even exists, do NOT even look at him! This works VERY well. Then when things are settled, I warn the guests that he does jump, we do allow it, please STAY CALM to reduce the jumping, and finally I do have a pretty solid "off." If the guests are calm, Renji tends not to jump or only jumps once or twice. I do NOT like guests petting him while he is up on them and I "correct" the guests if they do this.
I do hand them toys so they can interact with the dog in a way that redirects his energies.
One of the best commands, something we haven't taught but SHOULD teach, is the "place" command. "Go to your place/bed/mat/whatever" is an excellent command that can be used to tell the dog to go there and sit there, lay there, hang out there until told otherwise. You can have a mat or bed near the door so your dog can watch the goings-on but you can teach him to stay there while guests are coming in and wait for your release. Since he is a six month old pup, I would absolutely keep him on a leash- let him drag it around so if he does jump, you can redirect him. Have the guests help out in the training as well- if he jumps, they are to say "off," then stand straight and tall, turn their backs to the dog, and stand still. Dogs really don't like this because they're getting ignored! You tell your dog to sit, praise quietly when he does, and the guest calmly turns back around and resumes CALM petting! None of that frantic "GOODBOYGOODBOY scritchscritchscritch" stuff which incites tons of excitement, just a slow, quiet "gooood boy" and a slow pet to encourage calm behavior. If he jumps, they ignore again. So if he wants to meet guests, he had darn well better have his butt to the ground!
Please remember though, your dog is a PUPPY and has TONS of puppy exuberance! Less correction, more rewarding of good behavior! Now is also a GREAT time to jump back into obedience classes; they should stress proper greetings and jumping on people so you'll really benefit from a basic OB class at this point.
This is a good series of videos that teaches how to progress to stopping a dog from jumping. Definitely worth a look!