I forgot the essentials list but basically:
- Business cards with all your links. The more the better. Also try to have them in a display big enough to show off both sides, someone always messes with the pile and makes it hard to notice.
- 50-100 dollars in change. It's ideal if you have something to allow credit cards, but if you can't afford it like in my situation, you want change for people who come in with a huge bill to get like one print.
- Both sugary and salty foods, and plenty of water. The food is more if you have some nutritional problem but it's also good to keep yourself awake as you see yourself lacking in either. People tend to avoid your table if you're dozing off even if you think you're fine.
- If you don't know the situation of your table, pillows or something to keep your seat comfortable. The chairs WILL fuck up your back, the question is just how much, adapt to that.
- Tall displays, things that glow like string lights or a decoration. It's good to look up picture reference and see what catches your eye first because that'll be the point of view of a buyer. Wire displays are the best for prints and stickers, but you also want boxes and smaller panels to lift up a book or something. Remember, if it's just laying on the table, it's invisible to the buyer.
- Tape, table cloth, clothespins, scissors. Again, if your table situation isn't clear, you want anything possible to make sure everything fits and you won't drop the whole display with one bad movement.
- If you've got funds, a big vertical banner to stay behind you and make a visible spot from afar. Be careful with it, every con I see one fall and hit another artist on the way down, one time that was me.
As for what to bring other than your book - what fits the book! Prints are a given(A3,A4 and A5 are best, but make sure there's table space to display a bunch), especially if you've got good fanart, but make sure to have one or more of your original work in case a fan goes to check it out. Stickers are also good, buttons and pins are a bit more expensive but more eye-catching, and people also like small previews that they can get for free and weird things that aren't sold by most artists(lanyards, charms, felt plushies, fridge magnets anything you think could be cool).
Another tip is to have some offer to get free stuff or a discount. As an example, last con I put up a drawing of a Pokémon and gave free prints to whoever guessed it. Tons of people came by just to try and guess and some bought more things that they noticed they wanted.
That's... A lot, but mostly what comes to mind since I recently went to a con last month. Always keep in mind you're not there to sell unless people already buy your stuff like crazy (I haven't made a profit since the only time I actually got paid to be there), it's to make other artist friends and create interest in your work.