If it's outside, remember the wind!!!
Make sure everything doesn't blow away or tip over.
I remember one show i sold my photos at where there was a potter a couple booths down from me that had all of his really nice pots and vases all lined up on shelves for all to see.... annnnnnd then the front came thru and the winds picked up and almost ALL of his pieces blew over and broke!! Both tragic and astounding to watch!!
My booth almost lifted off but I hung onto the framework.
As for table cloth colors, nothing loud or bold. Neutral tan or grey would work. Even white is too much contrast.
Remember also... if everyone is buying your stuff, your prices are too low.
Take careful note of their comments and do not take them to heart. Hear what they wished something was or how it feels in their hands, those sort of things. This will give you a road map of sorts for the next batch of goodies to sell.
Lastly, there is no rhyme nor reason to any of it. What you might think will sell, won't and vise versa. Purely the whims of the buyer that day.
Remember... Do what you love and you will always have boxes full of things you love!!