Recall

t’s very important to make sure that your dog comes on recall no matter what distractions are around. Someday it may save your dog’s life. Better if dog comes and sits in front of you by default as it allows to easily collar or leash them as well as keep their attention.
You need to gradually increase the level of distractions. Don’t take dog from your backyard to dog park and expect him to listen. Practice in less distractive areas first. If you know he is not listening first 15 min or so, let him run it out, and then start practicing. Never allow your dog to get away with not listening to you, it will build a bad habit. Better not to call him than call and allow him to ignore you. 
You need to make sure to positively support recall. Often we call dogs just to put them on a leash, so they start avoiding to come over if they are not done playing. Call him, give him a treat and let him go back to play. It will build positive attitude towards recall.