You never get a second chance to make a first impression... unless you're a dog.
First impressions are important, and also one of the first steps in preparing your dog to meet other people and eventually other dogs. While meeting people is not exactly the same as meeting other canines, this should put you in the ballpark to see if your dog will do well in the dog park. Most owners can handle this training easy enough at home, but for some, group classes under the supervision of a professional trainer may be the way to start.
Now, I’m as guilty as the next person for not disciplining my dogs when they jump up to greet me, but if we want to properly socialize our dogs, then we must change our own behavior first. Consistently discouraging the behavior of jumping upon us is the best way for them to learn how to meet others. I realize this can be difficult, as they have clearly missed you since you’ve been gone forever (in dog-time)!
To prepare you and your furry friend to train for a new meet and greet, it helps to have a command or two down. The most useful would be; sit and stay. Having a command to offer them is far more productive than trying to stop them cold from the action of jumping up. Giving them an alternative, positive action to accomplish, followed by a reward of petting and/or a treat will create a happy atmosphere for both of you. It's just a matter of consistency and a little patience to get there. Remember; even if you forget just once a day, and reward them for the action of jumping up, that is enough to confuse them and will undo or stall any progress you've made.
When you think they are doing well with you, take advantage of visits from family and friends to try out the new skills. Ask the new person not to interact with the dog or give them a treat until the dog is adhering to the sit/stay command. You can also bring the leash into the mix to prepare for walks in public, so they also grow comfortable with that.
Practicing greetings with humans will give you a base-line to work with when you advance to the next step of introducing them to friendly doggies you know, and then eventually to new dogs.