On March 1st, I had the pleasure of doing wardrobe for Soweto Gospel Choir. The concert was part of Carnegie Hall's outreach program. Occasionally, I get calls for this sort of thing. I also have done one for Idina Menzel.
What the gig consists of is bringing a prep kit--Steamer, Iron, some thread/needles. I also bring Static Guard, a lint roller, stain removers, snips, a needlenose plyer, safety and straight pins,snaps and hooks of various sizes, suspender buttons, shirt buttons, collar stays, zipper wax and, of course, double stick tape!
I think it's important to bring tools with you. I have special brushes for painting and they come with me whenever I'm jobbed in for that. Sewing gig, I bring the needles I like, along with my shears, pins, tape measure, seam rippers and my Magic Cuffer.