Cancellation Policy Notification
Even though I started a discussion thread regarding charge-back disputes elsewhere, I feel this is important enough to include under best practices and the tip is this:
Always include a synopsis of your cancellation policy, short, sweet and stated clearly at the bottom of your automated transaction emails. This creates an information trail which documents that your cancellation policy was communicated to the guests multiple times when you had contact with them. I found this to be the piece of evidence which tipped the scales significantly in my favor during a recent dispute.