Definitely not a pro but I have done a few shows....
Those super florescent markers that you can write the sex and the price of the snake on top of the deli cup are priceless.
Depending on the light in the room and the morph, a simple table mounted light can in some cases really make your snakes look 10 times better.
Caresheets that go along with every sale is very important. Of course it should also refer them to BP.net AND have your contact info on them.
Make sure the people buying have your contact info!!! We all know that it is physically and mentally impossible to own only one ball python. And when people are happy with their snake, they will want to buy from YOU again.
Bring a set of probes and lubrication so you can verify / show the sex when making a sale.
Tips: (some may agree / disagree with these... they are my personal opinion)
1.) DON'T leave your snakes unattended.... EVER. If you are staying out of town, take them to the hotel with you. Snakes can and do get stolen from shows.... even after the public is kicked out and only the vendors have access.
2.) It is Ok to tell a kid who you know isn't going to buy that you don't want them to hold the snakes because they are stressed and need rest.
3.) It is OK to refuse a sale if you don't feel good about it.
4.) The BEST deals you will see are usually trades between vendors (especially at the very end of the show, or just after it has ended)
5.) It is just like gambling. Go in with your prices firm in your head. Have a clear game plan on what you plan to ask for each animal... and also the absolute minimum you will be willing to accept for each animal. Write it down. DO NOT exceed what you decide on before the show with a clear head.
6.) At a good show it is normal to spend more then you sell.
7.) ALWAYS have a bottle of hand sanitizer on your table. Before they touch your animals, make them use it.
8.) Don't feed the snakes for a week or two prior to the show. Always better for many reason for the snake to have an empty belly for the trip / show.
There is more but it is all I can think of at the moment. going to bed now. Good luck!