For me the first question is always, "What song(s) do I know that these people can relate to?"

You hit the nail right on the head there, Rita. The whole point of singing (for me, anyway) is to communicate - I'm singing for people, to involve and please them. It doesn't really matter whether it's Matty Groves or The Wild Rover, You Are My Sunshine or Raining In My Heart. It's such a wonderful feeling when someone comes up to you and says "Thank you for singing XXY. It brings back happy memories of when my grandad/mother used to sing that to us kids."

But ... I don't have a set list, don't make CD's, don't usually perform for money. So I just share my repertoire according to the situation. There are plenty of places I can (and do) go where I can perform an unaccompanied ballad if I want to.
Are you a mind-reader, or what?