Completely agree with Barbara, and I might add that in my experience, it's better to keep instrumentals to a minimum (at most 2 per set) unless you're playing for an audience of musicians. Most people really like singing, me included. Another thing my partner and I think about a lot is not going above or below the audience's head. I might enjoy knowing the whole history of a song, but most people like only an little of that, and not too much time between songs. A good 50-minute set is what we shoot for, which usually consists of 12 or 13 songs, and make the last set, if you do three, a little shorter. As soon as you build a following, take requests during the last set. Try to be gracious when someone requests something you don't play. My bane is requests for Jimmy Buffett songs. People who make such requests sometimes get angry if you say you don't play that one; It's like, "You've got a guitar and it's not electric. You're just being mean or you're lying about not playing Jimmy Buffett". One thing I've done is write my own songs in the style of Jimmy Buffett (one called "Coconuts For Brains") and others, like Kenny Rogers. The requestor never knows the difference, and the knowing audience has a little fun. But never, no never, talk down to your audience, like if they don't know as much as you do about music. If you find you're playing in a place that makes you feel like doing that, find another place. Have a signature last song. Mine was a somewhat obscene version (without being overt about it) of Goodnight Irene, for a long time. (I'll post the lyrics if you like). Or this might be a good time for an extended instrumental.

Good luck, Chet W.