Get to know the people who work at the mall where you have your booth. I don't care if it's an antique mall, an indoor flea market, or a vendor mall, if you really connect with the staff, it has great benefits for you as a seller.
For one thing, you have a built in buying audience. At some point, during just about every day, a staff person will be wandering past a booth on some kind of errand and something will catch their eye. They'll make a note of it, and return on break to check it out. BOOM! You've got a sale.
Just about everyone collects something. Finding out about the hobbies and interests of the people working in your mall lets you pick up some things you know have a good chance of being quick sales. In fact, I'll unpack something, clean it up, price it, and take it right to the front instead of putting it on the shelf.
Besides the obvious sales benefit to this approach, you'll also be deepening your relationship with the people who are there all day long watching over your stuff. You'll probably also find out that they're really neat people to boot!