I hope you don’t mind that I publish this, just in case other people would like to see it as well. Also sorry for the late reply!
-Plan ahead, try setting up a mock of your table at home so you know how you will set it up when you get there. Make sure you get there before the AA opens so you have time to set up (it takes longer than you would expect tbh)
-Doublecheck all the measurements, don’t plan for a 6x3 table and then realize when you get there the table is only 6x2.
-Bring a table cloth from home, it makes you look more professional versus just using the white plastic they usually put on them, and keeps things from skidding around.
-If you have a lot of art prints, consider building a print rig of some kind: http://aatoast.tumblr.com/post/52794396535/chuuface-i-built-it-most-artists-make-them (I’m currently using the last one and it’s the best rig I’ve tried so far). If it’s a larger con, most of the other artists are going to be using rigs like that, so it will make it a lot easier for people to see your work among all the others. If it’s a small con in a hallway or something then you probably don’t need it.
-Remember when setting up that people are going to mess with EVERYTHING, so make sure everything’s secure and stable. Don’t hang prints on the front of the table unless you really have to, it’s too low for people to really see it and also they will bump into them and tear them off if they aren’t secure.
-For anything over 5 dollars, try to price them in zeroes and fives only, so you don’t have to deal with one dollar bills that much; for example, you can sell like, 2 dollar buttons (which are popular btw, they are a pretty good moneymaker for someone starting out) but don’t sell prints for 7 dollars, or 11 dollars, because then everytime someone buys one you have to wrestle out 3 dollars change, 4 dollars change, because no one carries exact change at these things.
-Make sure you bring money from home to use for change, bring about 20 dollars in 1 dollar bills and 20 in fives, if you can (the dollars are essential if you’re going to be giving dollars in change, early in the con people usually have a lot of ATM money, which means 20s and 100s, so someone could come up to you early on and want a 2 dollar button but only have a 20 and you can’t count on having made enough sales by that point to make change for them).
-If you have a smart phone, look into getting a Square or a Paypal card reader, so you can accept credit card payments using your phone; that’s really useful.
-Bring water in bottles and snacks from home, con snacks are expensive.
-Bring a friend or table next to a friend, so you have someone to keep an eye on your table while you take bathroom breaks, or if you want to go to a panel or look around the hall or dealers’ room. I would not recommend going to many panels while tabling.
-Bring hand sanitizer and sanitize your hands before you put them anywhere near your mouth after handling any money or hugging people; con illness is actually a really serious problem, so don’t worry someone’s going to feel offended if you sanitize after touching them. I’ve picked up some pretty serious flus and sore throats from conventions.
-Bring something to do, either a game or art supplies to draw or something, so you aren’t sitting around bored when no one is walking by.
-WATCH ALL OF YOUR STUFF CAREFULLY. People steal a lot at cons. Keep your phone close/behind the table, as well as any game systems if you bring them. Keep an eye on your merch when people are hanging around your table. Keep track of where your money is at all times. Just make sure your important things aren’t ever sitting where someone could just walk by and pick it up. Don’t let your guard down during setup/cleanup either; recently someone swiped a book from my table after the hall had closed and the passerby was really sparse, so it can happen at any point. Something will probably be stolen from you at some point, just make sure it’s not your money/phone.
-If you’re in a back to back row like most AAs, be aware of the other artists around you and make sure you don’t do rude stuff by accident, like let eight of your friends sit behind your table with you and make the people sitting behind you really uncomfortable, or keep your stuff in a mess so other artists can’t get through easily, or bring super smelly foods or make a lot of noise, or have displays that encroach on other people’s table space. Don’t hang stuff on the back of your displays to try and get attention that should belong to the person behind you. Bathe every morning and wear deodorant, but not too much perfume or anything strong.
That’s about all I can think of off the top of my head… If anyone with con experience wants to add on to this post, feel free!