Lots. You just do it. Tough it out. I find that somehow the focus or excitement or adrenalin or something takes over and the cold fades into the background for awhile; however, a five or six-hour gig can be trying under those circumstances ... Along with the other suggestions, you've just got to throw yourself into the music when you hit the stage; concentrate on it, and not on the cold symptoms.

I'm suffering from a terrible cold right now, and I find that the only thing that I can really do is play my fiddle - it takes my mind off the cold and actually seems to make me feel better. Of course, that's me and this particular cold ...