If I can convince you of only one thing it is NOT to allow your dog to run around freely with other dogs.
Contrary to popular opinion pack animals do not play together; they practice fighting and when they get good at it they do it. I can’t tell you how many phone calls I get every week from desperate owners whose dogs have turned inexplicably aggressive.
We have a litter of Labrador pups at the moment and even at this young age you can see them biting necks, trying to pin each other down and testing to see how much pressure they need apply to get another pup to submit.
If we were to leave them together long enough we’d have aggressive dogs but of course, we won’t do that.
If you allow your dog to run free with other dogs the first thing you will lose is recall (your dog won’t come when called). Later, you will notice his ‘play’ becoming more boisterous as he chases other dogs around the park. Left unchecked, he will become aggressive to other dogs it’s as certain as night follows day.
You must teach your dog to IGNORE other dogs. Do not allow him to jump at other dogs or permit others to do it to him.
That way he/she will learn to be relaxed and comfortable in the company of his own kind.