I feel like all of the big ones have been mentioned, so I’m just going to hit on a few details off the top of my head:
A 10x10 EZ Up is a good starter canopy, and you can usually find them on eBay for a decent price. I’d spring for the side walls - even if you keep them rolled up during show hours, they’re helpful in securing the booth at night if needed (or for camping inside the booth if it’s that sort of event. Definitely get the carrier case with the rolly wheels. Also get one of the convertible hand trucks that switches from vertical to horizontal.
Those tents will walk (and even fly!) in a windstorm, so weights are your friend. The pool noodle trick is great for preventing rain damage.
Displaying items at eye level really helps, as does anything that you can do to engage people and get the item(s) in their hands. While we’re talking about hands, any small/easily grippable items should be kept close to where you’re sitting/standing, and displayed at a height that makes it easy for you to see their hands. The GF should allow you to create some great flat pack displays & risers.
If you’re selling jewelry/wearable items, bring a mirror and hang it visibly (many people will not ask for help - make it ready and available for them to find on their own). If you’re selling clothing, consider how you might create a private/changing area where folks can try things on. Have everything tagged, and be sure to create signs for products that need (or are more interesting with) any additional info.
LED lights are rad, generators are obnoxious. Have tons of biz cards, promo postcards & schwag if you’ve got it. If you have room, a portfolio is a great/effortless way to engage people and to give them an idea of what all you can do.
Table covers will give you a more professional/put together look, and as an added bonus, they’ll hide all the boxes and junk that you stash under the table. You can find the “banquet style” table covers on eBay in a wide array of colors. These are the ones where the table cover/skirt are all one piece, so they’re easy on & off.
Get comfortable chairs for you/your staff (manning a booth all alone really, really, really sucks - avoid it whenever possible). Director’s chairs are awesome. If you can, bring a spare chair; you never know when you’ll meet someone really interesting, and sometimes show-goers get overheated or overwhelmed. It’s a nice gesture to offer those folks a chance to sit and catch their breath and/or have some water. They will remember your kindness. On that note, keep some extra water on hand (I wouldn’t charge for it, just consider it advertising/hospitality) and maybe some granola bars or fruit.
I like to have some sort of floor covering - I’ve had sturdy rugs dedicated to this, but that interlocking foam flooring is good too. I’ve even seen people use astroturf. It gives the booth a finished look, and it’s super handy during wet or dusty shows. Helps to keep your merch cleaner, and also makes it more comfy and inviting for customers to come in.
plenty of change - coin, ones, fives & tens
small box of random booth supplies (duct tape, safety pins, pens, notebook, hooks, tools)
small 1st aid kit (and again: lots of water for everyone!)
breath mints, snacks, hand sanitizer & paper towels
a broom (you’ll rarely need it, but when you do, you’ll be sooo glad it’s there)
Make sure to organize everything the day before for an easy pack in (brownie points if you’re able to pack the car the night before). Get a good night’s rest the night before, and do not fall into the rabbit hole of staying up late before the show to finish that one last thing (even if you DO manage to finish it, it’s truly not worth being tired or cranky the next day when you have to be happy and “on” for 8-12 hrs).
Bring a partner, and be sure to give each other breaks so that nobody gets burnt out.
Walk the show, meet other vendors, get a feel for the crowd.
If sales are slow, don’t let it screw your whole attitude (which can wreck sales too). I remind myself that all it takes is one good customer to make my day, so I’m just waiting patiently and keeping my spirits up till that person comes along… and if they don’t show up, oh well. It happens - every show is a learning experience. I’ve had terrible shows where I didn’t even break even, but I met someone/some opportunity that totally redeemed the whole event.
Be kind to your fellow vendors. Especially during set up & break down (do NOT be that jerk who parks in the other guy’s booth while you’re loading out!) and treat your show organizers with respect. You may see these folks again, and it’s nice to have them on your side.
So. That turned in to an essay. Sorry about that. Hope there’s something useful in the midst of all the word vomit