Also decide if you want to only do overall quilting, pantos, or custom quilting. One friend only does overall or pantos as she feels it is her mission to do affordable quilting for quilters. She has a quick turnaround too.
Custom quilting gets involved with time spent to choose the design/s and do the recording of preferences. Type of thread used and amount. So many other costs are involved and yet you still get those who will complain and not want to pay. Therefore you need a disclaimer about the consequences of not paying the set price by a certain date.
Good luck.