Here are some that I feel are the most important parts of the post-show work that will be more for your business, rather than for your show side.
1: During the performance, make not of who is taking photographs, or filming. Find them afterwards and offer to pay for the developing if you can have copies of the ones with you in it. Or pay for a copy of the film. These go in your pamphlets, and web site. VERY IMPORTANT TO HAVE PUBLICITY SHOTS FROM YOUR SHOWS!!!
2: Thanks the person who hired you immediatly, and let them know it was a pleasure.
3: Send a thank-you e-mail, or phone call to the person who had hired you. It lets them know it wasn't about the money only. Increases chances of rebooks, and referals as they were a satisfied customer.
4: Check your inventory of brochures and business cards in case you need to order more.