I focus a lot on the walk.
When the walk is right, the mind is right and lots of problems will go away.
When l see a dog barking, lunging, growling, l usually see a dog who is also pulling, sniffing, and totally disconnected from the owner.
When l see a dog who is pulling and sniffing constantly, l usually see a dog who is wearing a harness, or a flat collar, with a very long leash held by an owner who is totally separated from the dog both physically and mentally.
When l see a well behaved dog, l see a dog who stays by the owner. l see a team - an owner being one with the dog on a deep level. I see a dog and an owner who know what each other wants without constant food dispensing or correction or verbal commands. I see harmony and unity.
Your dog will not behave if he is so disconnected from you that he obviously does not care what you think or want.
Your dog will not try to make the right decision that involves you if all he wants is to keep pulling away from you and sniffing everything that he finds to be more interesting than you.
To work on the walk is to work on building a solid relationship, which is the root of a well behaved dog - a dog who will try to make the right decision, view you as being the most relevant, and mind you more than his surrounding.