There's an old lady that I see most mornings doing a brisk walk, she always waves.
When a cyclist is going the other way down the other side of the street, there's usually a head-nod from both of us.
Joggers or dog-walkers, if they're coming at me, usually wave or make eye-contact.
Everybody else, nothing. Kids in particular, I would never think of waving to high schoolers, especially girls. Don't want to get arrested.
The exception is little kids, with their parents. If see a toddler has seen me coming, I give them a big smile and wave, they get all excited.