I suppose this should have been earlier in my reactive dog series.  Mea Culpa–my fault.   I wanted to mention some foundational behaviors, important moves, and management techniques that I suggest people put in their tool box for working with reactive dogs.  Some of these things I use more than others, some are really situational, and some are just enhanced basic behaviors.
Emergency U-turn– I very specifically teach a dog to turn around and walk the other way on cue when working with reactive dogs as a way to prevent reactions.  If you can get your dog to respond to a cue to turn and walk away at the sight of the stimulus (before the dog even has a moment to react) you can prevent the escalation of fear/anxiety/frustration.  I teach this by starting to teach the dog to simply turn around with me and walk the other way with little to no distractions … then work up to walking away from a toy or food on the ground and then from a ball being thrown, etc.  It is such a handy tool… you turn a corner and encounter a dog “Rewind!” and your dog hasn’t had the chance to react to the other dog before turning and walking away with you.
Where’s the yum?!–I use this if I’m in a situation where the dog can successfully focus on something other than the oncoming dog (so it would depend on the distance).  If there is a dog walking towards me at a distance (well below threshold), I may take a dog 20ft off the path and toss treats onto the ground and have the dog find the food.  I also use this for reactive dogs in my class if they get bothered by dogs entering and exiting.  I inform the handlers that people are coming in and have them play “where’s the yum!?” while the other dog enters as a way to keep their dog distracted.
Planning Walks and Escape Routes–When Shayne was at her most reactive, I spent considerable time planning our walks.  I knew where all the dogs lived, I knew which ones were fence fighter, which ones were out at about what time, where loose dogs lived, etc.  I got to know the walking schedules of the neighborhood dogs.  I took all this information to plan a route that would limit our exposure to things likely to cause her to react.  Once I had our basic route planned in my head (I wasn’t crazy enough to write it down, but if you have a particularly busy neighborhood, mapping it out can be helpful), I started thinking of escape routes.  Turn around here and go down this street if dog X is loose, walk into driveway A if dog Y is being walked on their flexi, yard B is fenced so I can’t get further away on that side for this stretch of the walk, etc.  I just wanted to have some plan of attack so I wouldn’t get stuck, like a deer in the headlights, if we were caught by surprise–for me it wasn’t a matter of mapping it out, the act of thinking about it and having mental solutions prepared me for the “what ifs.”  None of this was about treatment, but simply management and preventing a reaction (again, when there is a reaction their body is flushed with chemicals that make subsequent reactions more likely).
Name Game– Having a dog who can respond to their name with reliability is a really helpful behavior.  I think working really solid, really fast name response in high distraction environments is an important behavior to work on (*alternately a “watch” eye contact cue).  This is a cue that must be built up over many many repetitions in many many environments under varying levels of distraction.  This one is about being able to call your dog once and have them respond in even the most distracting environment–it’s a much better than the typical dog has.
Clicker Skills/Savvy–So much can be done using this simple plastic and metal noise box that I think it’s so important for handlers to learn the basic mechanics of using a clicker.  Clicker training is a two way street and the for the most benefit, the dogs should be clicker savvy and have a bit of ‘search’ drive for the click.  It’s so useful in reactivity that they are skills that I do heavily suggest, if not require.
Know your dogs’ reinforcers–I know, with out a doubt, that for Shayne, if I have Wellness CORE salmon and white fish canned dog food in a food tube that I can walk her past probably anything without any concerns.  For her, that food will keep her attention over almost anything.  If I encountered another dog on a small path and we had no exit (and it was before she was reliable with alternate behaviors), I could easily keep her from reacting by shoveling food in her face.
Hand Target–This is a foundational skill that I work on to have great reliability, even in stressful environments.   This behavior has so many options for how it can be used that it is one of the skills I keep at the top of my tool box.  Dog starts barking (a low level reaction)– “touch!”–dog turns their head to touch my hand for a treat.  In turning their head they break away from the stimulus and the reaction subsides.