I don't sell at craft fairs but I have quite a bit of experience with gun shows. I work for a promoter and sit at the door. Generally year to year at the different show locations the door numbers are the same. Keeping notes and records for all the different venues you sell at will help. I would talk with the other vendors and see what shows are great and which ones are not. That might help a little when deciding what shows to attend. Ensuring with the promoter that you are the only blacksmith at a show might help too.