I just finished my first craft fair a couple of weeks ago and found out the following. As mentioned above, a table and chairs; the fair I was at was indoors so there was no need for a cover. Water to drink, something for lunch or know of a fast food restaurant or the phone number to a pizza delivery service. Small items sold best or anything cheap. Cell phone cases sold the most, but must have them in many different sizes. Billfolds did not sell, but a roper wallet did, go figure. Bolo ties were not even looked at. Refrigerator magnets also sold like hot cakes (they were in the shape of little owls). High end items like small pictures didn't go at all.
As this was my first time I made an inventory of things to have on hand next time. Something to display the bolo ties better, like a form in the shape of a neck and body. Something to stick the magnets to, like a steel plate that was upright. A form to fill out for taxes after the show was over and a short term tax license. This may depend on location, state, city, country, etc. These are just a few things I came up with and I'm sure there are many more I didn't list. Just my three cents worth.