Being a nurse, I believe our training makes us able to talk to almost anyone. As I go about my day, I speak to people I pass on the street, other customers in a store, people in the same elevator, anywhere I may be. It can be as simple as a "good morning", or a comment about the weather, whatever you are comfortable saying, as long as it is pleasant and there's a smile in your voice.
Every parent likes to hear something kind about their child, or how pretty that color looks on them, it can be just about anything you notice. You would be surprised how few people don't respond or at least smile back. It doesn't cost me a thing, only a few seconds effort, and it pays me back just seeing people react.
My late mother was very shy, and she always marveled that I would speak to almost anyone. Why not? We all like to be recognized as unique human beings.