Some vendors make the mistake of minding their own business when it comes to their mall. Normally, minding your own business is a good thing. However, when you have a booth, it pays to be a little nosey.
I certainly don't mean you need to get nosey on a personal level. I want you to be nosey about the other booths. Walk around and shop your store every chance you get. There are a number of reasons why this is a good idea.
Most importantly, you need to be aware of how much other vendors are charging for similar items. What is the price range for dressers, chests, farm tables, etc? Are the most expensive ones selling or do they just sit there for months on end? You will likely see items very similar to things you have in your booth. Your customers will see them all, too. How does your item compare in display and condition? How does your item compare in price? Your prices need to be in the same ballpark with other booths in your store.
While you are browsing the store, there's always the chance that you will spot something from your booth. It's funny. So many shoppers pick things up, then change their mind a little later. Do they put the item back where they found it? Usually not. In a vintage mall, it's often hard for them to remember where they got it from.
While you are browsing, it's a good time to unobtrusively notice other customers. Without staring or making customers uncomfortable, try to notice which booths they walk into and which booths they walk past. If you notice a trend with certain booths, try to figure out what it is that makes that booth particularly inviting (or not). I highly recommend looking like a shopper while you are doing this. Have your purse on your shoulder. If you seem like a worker, an honest customer might get the creepy feeling they are being watched as if they are a shoplifter or something. :-D
Last, but not least, as you walk around, if you come across another vendor working in their booth, take the time to chat. Most vendors are WONDERFUL when it comes to helping each other out. Do not think of them as competition. Lots of wonderful booths = lots of customers coming to the store. Help each other!