First, I would practice an auto-sit every time you stop. That way, when you are walking up to the person, your pup knows to sit rather than to react to the strange dog.
I can't think of a way to teach this without another dog... except maybe, when Keely gets excited and wants to go see/sniff/explore something, get her to focus on you, sit, and then wait. Then her reward is going and doing what she wants to do. When she gets it really well, decide to keep walking a few times and treat instead. Dogs have a hard time generalizing, but with some luck, Keely will associate her own excitement with calm behaviors. NEVER let her pull you to a tree, patch of grass, anything. And if she isn't giving you attention and doing what you ask? Turn around and walk away from the thing she wants.
I can't think of a way to teach this without another dog... except maybe, when Keely gets excited and wants to go see/sniff/explore something, get her to focus on you, sit, and then wait. Then her reward is going and doing what she wants to do. When she gets it really well, decide to keep walking a few times and treat instead. Dogs have a hard time generalizing, but with some luck, Keely will associate her own excitement with calm behaviors. NEVER let her pull you to a tree, patch of grass, anything. And if she isn't giving you attention and doing what you ask? Turn around and walk away from the thing she wants.