According to this article at Furniture World online magazine, a lot.  I find it fascinating the little things stores can do to improve business.  First impressions and superficiality are the name of the game.

The location of the entrance, the signage (color, content, location), the architecture, landscaping, and color scheme.  Especially the entrance.  There's a store with a particularly interesting entryway — a map to the different sections of the store is on the floor as customers walk in, which 1) gives the customers an idea of where to go, and 2) causes the customer to pause long enough to give the sales people time to casually meander over "without being overbearing".

Interesting stuff.

Customers Judge You In The Blink Of An Eye