Do not reward your dog for his bad behavior by giving him what he wants. Do not pet or praise your dog until all four of his feet are firmly planted on the ground. If your dog is jumping on you, turn your body slightly so he rebounds off you and tell him "No jump!" Or catch his forelegs and hold him away from you, then drop his front end to the floor with the command to "No jump!" You may have to do this several times before your dog realizes that you do not share his enthusiasm. If your dog persists in jumping, you may (with caution) raise your knee as he leaps, accompanied by a firm "No jump!" Use this correction with care as you could injure your dog. Escalate the force of your correction only as needed to produce the desired result.
Now praise your dog and pet him for as long as his feet remain on the floor. If your dog starts crawling up your body as you praise him, stop the praise and push him off with a "No jump!" Praise him again as soon as his feet return to the floor. Timing is important, remember you have to tell him when he is doing it right. Use a quiet, calm voice when praising the excitable dog. The high pitched, praising voice you would normally use for reinforcing good behavior may wind him up into repeating his unwelcome behavior. Try not to set your dog up for failure. Praise is so important. If your dog does not receive the attention he is craving, he will court any response from you, even a reprimand.
What if your dog jumps on others? Ask one of your friends to approach your dog when he is leashed and under your control. Leave some slack in the leash. If your dog leaps to jump on your friend he will correct himself when he reaches the end of the slack lead. Your friend may then reapproach the dog, if he leaps again, he will correct himself. You should accompany his attempts to leap with the command to "No jump!" Tell him he is a good boy when his feet remain on the floor and allow your friend to complete his approach and praise your dog. Use one word or phrase when correcting your dog, either "off" or "no jump". Do not use "down", this command should only be used when you want your dog in the lying down position.
A word about leash corrections. Do not string your dog up on a taut leash. Some dogs learn to pull against a tight lead, gasping and choking every inch of the way. In order for the dog to learn that his behavior has consequences, leave the leash loose and he will correct himself when he reaches the end of the slack. Once he connects his behavior (jumping) with the correction (the leash tightening), you will see him change his behavior to avoid the correction. He will also learn to connect his good behavior (not jumping) with his reward (your praise).
If your dog gets excited around strangers, teach him to shake hands, this puts brakes on his behavior as he has to think about sitting and presenting a paw. This is also a good tool for training a timid dog to be approached by strangers.