Dick - there are no rules. If you're a pro performer, but not a star,   you have to work out your own salvation on the stage. If you can make trad folk work for you, all I can say is well done!

I suppose I do get fed up occasionally with the job of lifting the mood of the room after some particularly earnest and demanding artistry, be it contemporary or trad.
Still, its a skill and you don't learn to do it in five minutes or by practising at home, although obviously that does come into the equation somewhere.

I suppose more than anything you learn it by having the guts to take on audiences where there is the possibility of failure, and slowly you learn what you were doing wrong. You learn to read audiences.

And when you know about folk, then you start to get a handle on folk music.