Dogs jump to greet you or to get your attention. To stop this habit try these suggestions.
Squat down to greet your dog. He wants to see your face.
Teach your dog to sit. Practice "sit" in situations where your dog jumps. Give him praise/attention only when he's sitting.
Be consistent: do not allow your dog to jump during play or when you have old clothes on (your dog doesn't know the difference between your old jeans and your best suit). Don't allow a puppy to jump; he will continue to jump when he gets big.
Do not let visitors or kids allow the dog to jump.
When correcting a jumping dog, use the command "OFF" not "down". "Down" means lay down. If you use the same word with two different meanings it is confusing to your dog. Choosing a different word for jumping or getting off of things i.e. the couch, it is far less confusing to the dog.