Highlight the booth with a few very large, very impressive reproductions in differing dimensions, both framed and in gallery wraps. These should be eye-catching and represent some of your best work. You may not end up selling any of these larger, more expensive photographs at that particular event, but they will draw people in to see your other photographs, or they may choose to purchase smaller versions of the larger photographs on display.
You don't have to tell people much about your work; you can let it speak for itself. Show variety by displaying collections of photographs that capture the facets of your photography. If you do still life, portraiture and scenic works, represent each facet with a separate display of photos in differing sizes and orientation. Try for an appealing blend of colors, with one color that particularly stands out.
It's important to be accessible to all customers, including those who can't or don't wish to spend a lot of money on art. Put several inexpensive matted photographs in smaller sizes on display and set out boxes of these photos for customers to sift through. You can also sell note cards and magnets featuring your photographs. You may end up making more money on customers who spend $5, $10 and $20 than on those who spend $100 or more.
Don't put your boxes of matted smaller photos in the front of your booth. In fact, don't put any materials right out in front. Use your most impressive works to draw admiring customers all the way into the booth, then let them see the smaller collections and brochures. If you have a free gift for potential customers, place it slightly within the booth where they can see it, but can't just grab it and walk by.