Based on your location, I'm guessing it's an indoor show?
Do you know how the room will be set up or in a school's hallways? I try to scout my location a few days in advance and have had to redesign my booth to fit odd spaces. You want your display to be eye-catching and attractive but not to much to distract from or camouflage the products. Lighting is very important; we did shows 'back in the day' and LED lights were still new. Since powerful and clean LED lights are abundant now, that could even run on batteries, I would light as a photographer once told me, "Every curve gets a highlight and every highlight gets a curve" (It was a weird conversation, but you get the idea).
I liked to keep the register/money/invoice exchanging station out of site - when people browse, they don't want to be 'hit over the head' with 'GIVE ME YOUR MONEY!!!' until they are ready to make that decision on their own. However, feel free to start a conversation about the product or process if someone picks something up to get a closer look.
Halitech said it above - smile and be confident. Some shoppers will be trolls and maybe not even know it by saying things like, "I can get that cheaper at Wal-Mart" - be prepared for some negative feedback and prepare your responses in advance because it will surprise you the first time you hear it. Be positive and polite.
HAVE A GREAT TIME! It's scary having your first show. You'll learn quickly what venues match your offerings best. Don't be afraid to change the types of show you sell at; high-school crafts, juried art shows, etc.