Touch. Place. Focus.
The behaviors you teach are your tools to navigate a world with ubiquitous distractions. If your dog is having trouble focusing on you while in a new environment here are a few tools you can use.
For a dog to shift their attention off of something intensely exciting two things are required.
A high enough value reward (or the reliable anticipation of one)
Distance
Re-direction behavior
Situation: Tsu and I are walking on a trail and a squirrel pops out in front of us. (Tsu has high prey drive, and thus the prospect of a squirrel chase gets her pupils dilated)
I will call Tsu away from the squirrel using the cue "Place" - this is her default cue (more on those later). In this context it is being used as a redirection behavior.
Tsu won't turn away from the sight of a squirrel, unless:
She knows I have pieces of baked sweet potato (or later is patterned to expect that kind of reward when she hears the cue). Very high value reward.
There's enough distance from us to the squirrel that it is not an impending emergency
Touch = touch your nose to my palm. (if my palm is in the opposite direction of the distraction, i can maintain pooch's focus and guide the dog out of view of the squirrel, other dog, car, stroller, bicyclist, cat, or curious gopher. If you teach your dog to walk whilst keeping their nose on your palm you can literally position them anywhere so they can't see what's bothering them)
Place = stand between my legs and look up at me. I love this behavior because of the degree of control I have over her physical position and proximity to myself.
Focus = Make eye contact with me. If you're looking at me, you're not looking at the pant-less squirrel (Tsu scared said pants off said squirrel)