We charge nothing up front, but do require written confirmation of booking. Payment at the end of the gig in the form of a cheque.
Hey, this is Scotland! I know nearly all my customers and those I do not know, I can check up on from a national database.
If you trust people, 99% will trust you back. In that respect, musicians are like dogs and horses! If you want to learn how to deal with producers, A&R, musicians, managers etc., watch the Dog Whisperer National Geographic Channel - Dog Whisperer