Here’s a list of a few things I learned:
There was loudness constantly. Stand up and speak loud to be heard.
Have a price sign. The first day I had no sign, and some interested people were probably disenchanted and turned away because I tried telling them the price, and failed at tip#1.
There’s a difference between being an artist and being a vendor. Booth fees are typically less for an artist. An artist produces everything themselves to sell, a vendor brings things they buy at wholesale to sell.
Bringing a cooler with ice and bottled water and soda and energy drinks is way awesome to stay cool.
Bringing a cooler with ice and bottled water and soda and energy drinks is way not awesome to lug to and from your car to your booth, due to weight.
Listen to the feedback of people who don’t buy from you. Offer to make them what they want and ship it.
Bring something to keep yourself occupied at the booth between customers. Try to have it be an unfinished art piece you are painting, or something you have cut out and are assembling. It looks professional. A video game is not. It will get boring.
Put the product in the customers hands.
Make sure you have at least 1 other person with you. 3 or 4 is ideal. You can rotate around seeing the competition and the events, get help reaching for things, and always having at least one person engaging with people and telling them what your product can do for them. Bathroom breaks are important too.
*Bonus~ it also significantly increases your booth being seen if one of those assistants are cosplayed up.