Contractual Agreement
Since Body Art By Erin is a business based on supplying a service in exchange for money, I find it is a good idea to make sure that each party knows exactly what that service entails. The best way to do that is with a signed contractual agreement.
Upon arriving at your function and prior to setting up, I will go over a very simple contract that will explain what services Body Art By Erin is expected to provide in exchange for the money that is being paid. This way everyone is on the same page before the event begins.