I have worked the shows here in Illinois, both for myself as well as for other companies.
*Location of your booth is huge, the closer to the middle the better, many times people will walk past the first rows to see if there is a better deal, but for some reason they never get all the way to the end, unless they are leaving.
*Get a girl.......biggest seller in your booth will be a decent looking female
*Give away to the kids, if your dealing plastics, they are cheap but giving a small sample to a kid often can be a game changer, I have seen it with the guys that make the Musky tubes on a broom handle, they give a kid one, and then Dad turns around and buys 1 or 2 more.
*Square Up and PayPal both now have virtual credit card terminals that work on a smart phone, both charge somewhere close to 2.75%
* Again as mentioned smile, shake hands, and kiss babies no sitting in a chair
* A small fish tank or something to show the action of the plastics
* Make sure you have biz cards, so many times I see guys at a show, they sell stuff but the customer has no idea how to get more if they like them. Even if you make a couple sample packets for the kids staple a biz card to it, that way when dad steals it and finds out how good it is, they can get more.
* got a website? Make sure it is the best it can be, during and after your show people will visit, make sure it is easy to navigate, keeps their attention