We have done the flea market in What Cheer, Iowa which is usually a 3 day event. They open the gates for vendors as early as Thursday night, early birds can shop on Friday then Saturday and Sunday are their big days. We try to get there Thursday nite if we don't reserve a spot then we can get the pick of the field, and have things ready to go when the early birds come.
We stay with our stuff and camp there, some places allow you to do that, there is a hotel not too far away, but it's part of the adventure when you camp it out.
Most times they give you measurements for your booth, I've been there enough I know how to lay my booth out. I like to make people "walk through" my booth by creating a path, that way they hav better opportunity to see everything. Make sure it's decorated 'cute' 'nice' whatever you want to say- make people want to shop your booth.
We pack for camping, and for selling. One year we even brought an air conditioner that we rigged in the topper of our truck because it was so hot! Totally hillbillied that one... but we had a good time.
If this is your first one, you can request to be put near electricity, or you may have to wing it and find out where the good booths are next year. We have it down to a science, but it took about 3 flea markets to figure it out.
Tarps and big clamps are a must! Between the weather and if it's a two day event... you'll want to be able to duck and cover quickly.
Setting up by a food stand or bathrooms is great too, everyone wants to eat or needs to go to the bathroom at some given time during the day so they will have to walk past your booth.
Well- I should stop rambling... those are a few pointers... I'm sure more people on here have some great ideas too!