I sell almost exclusively at fairs. I have 4 identical folding tables, plus some others I sometimes through in for extra work/display space. I use a 10x10 "EZ Up" tent. I had to buy the heavy duty (blue) top for it, as the one it came with (white) was ruined the first year (at NJRK: New Jersey Renaissance Kingdom). I have a variety of "table toppers": display shelving. Ranging from mug racks (a post with spindles coming out) that I use for keyrings, Christmas ornaments and such, to a pair of folding corner shelves. Sometimes I decorate the tent, sometimes not. It really depends on the event. But I ALWAYS cover the tables my work is on, and I try to keep my stock boxes underneath.
Also, I try to always bring stuff to work on. This helps with the "Do you do that?" (Yeah, and not some ol' cowboy ) and the "how is that done?"
I've attached some pics of various displays I've had. My good friend Ann McGrath is in the one. We often shared space when I lived up north - it cut cost and allowed us both to not have to fill the whole tent with stock.
For me, some fairs go REALLY well, and others are meager. It's a matter of trial and error.