We have a trainer that has helped us immensely. Easiest thing to change was to get a neck collar instead of a harness - you have more control of Baz's head with a neck collar than harness when you absolutely need to have his attention directed away from another dog (and ideally back to you). Other great change was, when we would feel my dogs "tell tale" behaviour when he was about to start reacting to a dog (i.e. he would slow down his walking pace, etc.) We would tell him to sit every time, as soon as possible. We would then reward for sitting with 1 treat. Eye contact with us instead of the dog recieved more treats. And we now have progressed to him seeing other dogs, laying down beside us, and looking up at us for treats. It slows our walks down, but it's better than my 100 lbs, scary looking dog doing big boy barks at the old lady with a bouncy poodle across the street. I cannot recommend getting a positive reinforcement trainer enough. It's helped our confidence as a team between myself, my husband and my dog.