I've been to many arts and crafts shows, etc., both to support my wife's various ventures (she doesn't do them anymore) and as a customer/browser.
I've learned a few things:
1. You need a ringer. You don't have to lie, but every ten minutes or so walk in from the crowd and start asking your "wife" the photographer questions and ooh and ah over her work. Don't just sit in a chair in the back under the shade. Get out there occasionally and pretend to be a stranger who is enthralled. You don't have to lie, as mentioned. Just ask her questions like, "wow, I like this one. What made you choose this subject? How much is it? it would look great in my dining room," etc.
2. Be friendly, friendly, friendly (I'm talking about the photographer). Don't be pushy, but talk to people. Sales is as much about personality as it is product. You want to make that human connection. But it has to be sincere. Insincere flattery is offensive, but if you can compliment people and mean it, they love it. Works well. Always ask the ladies about their children and the guys about their hobbies. Women love to talk about their kids, and the more they think they can connect with you, the likelier it is they'll buy. Too often I see the artists/photographers/craftsmen, etc. sitting in the back doing a crossword puzzle, looking very unapproachable. And sometimes they even have a frown all day. Never let 'em see you frown. Frowning is bad. Smiling good. Doesn't matter what your teeth look like. A genuine smile is a treasure. I knew lady once (sorry to digress) who would cover her mouth every single time she laughed. She didn't even realize she was doing it, but it was because of her bad teeth. So what? A real smile transcends all that crap.
3. No snobbery. When the amateurs come around asking about F-stop, equipment, etc., answer their questions with lots of good knowledge. Don't feel intimidated, but rather, feel flattered. Encourage them to do it too if they ask. They aren't competition (yet), just curious about how you work. It's unlikely they will say, "A rebel? Man, anyone can shoot with a rebel." They probably won't knock you for megapixels or whatnot. They just want someone to connect with. Make THEM feel special by returning compliments: "Wow, you know a lot about this stuff. Sounds like you do some professional work too."
4. CHILDREN. Now this is the gravy: At all those arts and crafts fairs the things that appeal to children sell like crazy. Moms often have this guilt complex that we guys don't have when it comes to buying things for themselves, and wives often don't appreciate the fun stuff we guys like. But when it comes to buying stuff for their kids? Well, they pull out all the stops. It's not just toys and junk they don't need (like colored sand in a bottle, inflatable giant hammers and crap like that), but if they think something will look good in Johnny's or little Becky's room they'll be more likely to buy it.
It might not be what you want to shoot or sell, but if you have a ton of photos that kids like (castles, race cars, military jets, baseball stuff....any sports stuff....horses, ponies, horses and ponies, and stuff like that, moms might get it.
I wouldn't recommend velvet Elvis's, however. Man, who thought up that stuff?
Thank you. 
