Seeing a lowly author sitting at a table for one, a stack of books on one end, and on the other end, a sharpie pen ready for autographs, and not a fan in sight, gives Mr. Obie Joe the heebie jeebies. Apparently many bookstores, particularly chain stores, feel the same way, which is why many authors are banned from securing a booking unless you's somebody, or knows somebody.
There is a way, though. Make your reading/signing an event. Granted this is easier to do if you've got a nonfiction title, but even a fiction title can do it (see the enormous turnout for some YA titles). One author we're working with has a pop culture book. For his appearances, he's planning a quiz show format. He'll ask people in the audience, and he'll solicit people walking by. If the lucky accostee has the correct answer, the author awards a prize. Even without a spinning, glittery wheel, he's got an audience for his appearance, and then his book.
Think of a way to make a "show" from your book. If your book is about tea party sets, pack 'em up and bring them to the store to make an educational session. The amazing publicist Lauren Cerand mixes music, books, and other performances in her Upstairs at the Square events at a Barnes & Noble in NYC, and the crowds it attracts, both in loyalty and numbers, is amazing.
As wonderful as you authors are, by yourself, you're not enough for a successful bookstore appearance.