get a blanket to cover your table. and don't barter with people on price lol

Don't get raped.

Never did that myself, so about all the advice I could probably give ya is to have a few samples set up to kinda advertise yourself, keeping the mature and clean things separate in the art book/folder you may place them in if you do that, as well as nice clear labels on pricing below each kind of thing your offering (such as sketches, inks, maybe colors. I'd try to sort them and have a 2-3 examples of each if you can as well), probably would be good things to do as well.

Do get a blanket to cover your stuff up / Have a container to lock your things away at night.
Stay hydrated and make sure you have some sort of snacks
Wonder around and have a break every once in awhile
And unlike Balun_Roo...I'd say barter prices with customers on certain occasions...if a person is like "I'll think about it"...try and break a deal with them...any money is good money ya know...