Whenever possible I'll wear a suede vest with pockets for a capo and extra picks. I tend to wear darker color shirts to contrast against the light color of my guitar and mandolin. Not to mention my cleanest jeans and boots or suede wingtips. In church I'll wear a suit with the jacket on - the other guys tend to want to perform in their shirtsleeves. And I try to wear one of my Jerry Garcia ties if I'm going to wear a tie.