Sit is very helpful, but not required.
As with any training, the fewer distractions when you get started on a behavior, the easier it will be on your dog.
Treat either in place or on the floor.
For any jumping behavior:
Jumping on you when you are seated:
Jumping on you when you are standing:
This is similar to the instructions above. You may want to add the following:
Practice these steps EVERY TIME your dog performs the unwanted behavior.
Remember that sometimes behaviors get worse before they get better. This is called an “extinction burst”. Think about a child who has always been indulged for bad behavior that is finally told “No”. He’s not going to get quieter. At first he’s probably going to throw an all out tantrum trying to get his way. He will finally give up once he knows that he’s wasting energy and can get what he wants / needs in another way.
BE CONSISTENT! This cannot be stressed enough. If you give in, you could potentially make the behavior harder to address.
Your dog should be keeping all four feet on the floor when he/she greets you, and should not be jumping up on you when you are sitting down.