Played a gig the other night (my ragtime piano ensemble) and beforehand the keyboard guy and I discussed what to wear. We settled on what we call "Farrell's," after the ice cream parlour.
His partner for the four-hand pieces arrived in a colorful top, black pants (picked up some of the shading), and a matching necklace. Looking at the audience (a local community service group, mostly seniors), she remarked, "I'm overdressed."
Afterwards, I told her about my one band director, who is often the oboe soloist. She arrives wearing something that's clearly beyond the curve; walking in, you can tell that she is The Soloist. And for an announcement in rehearsal, she did a riff on stagewear and being attired in a "uniform" that helps you do your job with confidence and from a position of authority.
This works in all sorts of situations. Recently I attended a media event to announce the placement of new bike racks in our DT, carefully selecting my attire. Guess who the media gravitated to for further comment.
At most of my entertainment gigs, my client walks up and says, "I can tell that you are the square dance caller."
At civic meetings, I've noticed that the person portraying the role of the city attorney is typecast as a matched suit with tie, even for a night meeting with casually-dressed members of the planning boards. At one of my previous municipal gigs, the hired consultant always wore comfortable colorful tennis shoes, sweat pants or jeans, and casual shirts. Her responses to requests for a professional opinion always matched her outfit: "I'll have to get back to you on that."
In sum: feel good about strapping on your armor as you head into battle!