Bring cash, leave the credit cards at home. At a big show there'll be more to buy than you should and you will if you have plastic.
If I bring plastic, and bust it out right as I'm about to buy, but quickly toss in, "Hey, can I get an extra 5% off if I pay with cash?" will that work, or just upset the dealers? I know CC fee's are usually right around 5%, plus a bit depending on what company I use... *coughAMEXcough* BTW, I'm not afraid to bring plastic. I'm good at sticking to budgets... really good at it. I'm a guy who likes to get good deals on stuff, and I won't buy unless it's a good deal.
This thread has been very helpful for me too. I'm looking forward to attending my first coin show in about 15 years the 1st weekend of August. Of course, back then most of the shows I went to were combined with sports cards ( and I wasn't buying coins ) I have gone to quite a few gun shows in the last few years and I'm guessing "the art of the deal" I've learned at those shows will apply. If you think dodging backpacks full of coins is bad try getting tapped on the shoulder and realizing it's a rifle barrel someone has over their shoulder..lol
I'm planning on Saturday at the moment. I'll post what I'm wearing before I head out in the morning. Feel free to say "hi" if your group ends up going the same day