From one Cooper to another ... be sure to take your Cooper to new environments, places where you want to take him and let everyone there hug and love on him. Don't let them do it unless he's calm and not scared though. He needs to get positive reinforcement when he's calm that strange places are good and so are the people there.
My Cooper has done nothing but get friendlier and friendlier since he was a puppy. Now, he gets really offended if he approaches someone and they ignore him.