i totally agree not to take him to places where there are unleashed dogs, because of his issues he will just get owrse. kind of setting him up for failure. what i would do is try and find people you know that have calm submissive dogs, maybe one on on play time. you still need to watch his signals and keep him calm before he meets the calm dog. when his nose start smelling thats the curiousity and if his other signals are calm, i would take him up to the other dog. no head on meeting try and let him smell the other dogs privates. then call him back and treat and praise him, then walk together with the other dog. if the meeting doesn't go smoothly and he gets aggressive i would maually correct him put him down in a submissive postion beside the other dog, hold him there till he relaxs. then have him repeat the greeting., tell him to be nice this time, usually they will do two things they will repeat the greeting nicely and walk away, or just avoid and walk away. just make sure the other dog is very calm and submissive, goldens work well for this. but your timing has to be right if something goes amiss. by correcting him in the act tells him its not allowed. i would never try this with anyone who has a dog that tends to be dominant, or aggressive. but there are plenty of dogs that you can work with that have calm temps. this has worked well with my gsd. if you ever encounter an aggressive dog, you need to take care of the problem not him. pepper spray, dominant stance, etc. never let him take care of it. a private trainer can set you up in these encounters and teaqch you how to react in situations so that your dog understands what you want and don't want. he will be more confident if you are and he will trust you to protect him from negative encounters,. etc.