Here’s a tip when doing a book signing: have a poster made of your book cover that can either be stood on the desk your at or on a stand close by. That will draw in the readers. Another is for you to stand in front of the desk and (in the beginning) force yourself to talk to people going by. You seem less intimidating than if you're sitting behind a desk or table. Plus, a reader is more likely to buy your book if he or she has talked with you. Have something ready to give to the ones you call over. Maybe a bookmark, you can make those up yourselves or have a local copy shop do them. Be sure your web or email address is on it. This way, after you sign a book for them, you can suggest they let you know what they thought of your book.
Just imagine how intimidating you might look to me, the average reader, walking by: you're this big-time author with your published book sitting there daring me to come pick it up; and what if I don't want to buy it -- are you going to spit on me?; or what if I ask some stupid question?; or what if I get so nervous I blurt out something really dorky like, You look a lot like my Aunt Tilly who never wears underwear? Those are things flashing through my head as I glance your way, then avert my eyes before you catch me. Then, you smile and invite me over, tell me a little about the book (that spiel you've been practicing on friends). Well, hey, you're not so bad after all.
Just as we as writers think it's scary to do book signings, readers can find it scary to approach a writer. But while they may not know what to say to you, you do know something you can talk to them about -- your book. And who knows your book better than you? Who believes in your book more than you?
And once again, all of it becomes easier with practice. Opening lines to draw people over, answers to questions you repeatedly get, making small talk, participating on panels at conferences, etc. -- difficult in the beginning, but more natural feeling as you do it. You may be someone who grows to love the business of meeting your "public," or you may be someone who never gets used to it totally. But you *can* do it.
4 months ago