I haven't actually done a craft show with my jewelry (I'm not quite there yet), but I have done shows with my sister's gift baskets and I have been to a lot of craft shows. So, FWIW, I have the following suggestions -
Some of the nicest jewelry tables I have seen have height - you need to get at least some of your pieces vertical somehow. This makes them not only more visible but also more appealing. If you can't afford actual jewelry busts, get creative. At one craft show I saw one woman draping colored cloths over rolls of paper toweling to display necklaces. Another one used a tree branch in a plant pot to hang bracelets. Even a small gift box or shoebox wrapped in pretty paper can be used as a platform for a display. Use your imagination.
Make sure you have some kind of additional lighting. The fluorescent lighting most places that host craft shows have is inadequate. I'm not saying you have to go out and buy several OTT-lites or anything like that, just get some kind of clear, white light.
Freestanding mirrors are a good idea too, so your customers can try on the jewelry and see what it looks like on them. I saw a lot of jewerly tables at craft shows with no mirrors. Women were taking their compacts out of their purses trying to see what the jewelry looked like on them.
Lastly, as for your table decorations, keep it simple so as not to distract from your jewelry. If you have "company" colors, try to use those or if not, use your favorite colors. Black or white always works as a table top, and you can use any color skirting with either one. My sister and I sold the gift baskets at holiday shows...we had a white table covering with gold threads running through it and since it was the holidays, we did red and green skirting. It looked very pretty.
HTH and good luck!! Take lots of pictures!! :D