I have only ever done 1 craft fair. That was because I had made lots of things just for fun and needed to get rid of them for the space.
I think not to overprice your makes. I priced my things just to cover materials used and a tiny bit more added. I don't run a business so was just happy to let my prices stay low. Another thing is nice packaging. I put my things in cello bags. For things other than cards I added a fancy packaging top to cover the opening of the bag.
How you display is another way to grab the interest of the buyers. I used those small small vanity case type boxes in different sizes and had different levels.
I cleared about £80, so was well pleased.
If you have a website or FB page it is worth having some business cards made (I didn't), as lots of people asked me for a card.
There is lots of info on the internet, but I think the main thing is to enjoy it. I was so nervous thinking that none would like my makes, but once you are there and get caught up in it all, you will get a real buzz.
The craft fair that I went to was at a local community hall. I would not have wanted a big affair...some of the bigger fairs need you to have insurance.
Good luck and don't be too disheartened if you don't sell much..there were stall holders at the one I attended, who sold very little. I suppose it all depends on how different your stuff is, the price and if its nicely made.