Some writers may consider this the "dreaded" book signing that they must endure to help their book sell. But with a little preparation and effort, it may just end up a success. Here are some tips:
1) Scope the layout beforehand by visiting the bookstore and introducing yourself to the staff. You'll see how much room you'll have, what supplies they already have and can get a feel for traffic.
2) While in the store, don't be afraid to suggest locations--you may want to hang out and see where customers naturally walk.
3) Explain to the manager what you'll be bringing. You can also solicit the staff's help by seeing if they'll put up a poster and really talk up your book and your signing beforehand. It helps if you give them a little treat for doing this.
4) Get the word out to local newspapers, online chat groups and any other networking groups you might have.
5) Make sure you bring the following that day: extra pens, a sign-up sheet for an email newsletter, candy or treats (gets the childrens' attention and the parents will follow) and consider having a drawing for a promotional-related prize, i.e. t-shirt with your book's picture, magnets, calendar, etc...
6) If they don't come to you, go to them. Get up and walk around.
7) Have a larger sign or banner at eye-level to the customers. If you put something on an easel, it will get their attention and help them notice you sitting there.
8) Remember this is about contacts, not just how many books you sell.