So you’re doing your first book-signing.
A handy list of things to put in the back of your car from our friends the Romance Writers (add or subtract according to your situation and preferences):
- Tablecloth
- Candies* and dish
- Flowers
- Props (e.g. if you have a nautical adventure, a model ship)
- Scissors and tape (blue tape, duct tape, and cellophane tape.)
- Pens — book-signing and other. Make sure one is a Sharpie.
- Mailing list
- Bibliography
- Book cover stickers
- Business cards
- Water/water bottle with screw-on cap
- Change for parking meters
- A brief biography for the person who will be introducing you
- Emergency personal supplies/first aid kit
- Book marks
- Posters/flyers/advertisements
- Loudspeaker announcements
- Book stands
- Blank card stock and marker
- Presentation materials (projector, easel chart, etc.)
- Lightweight table
- Lightweight folding chair
- Camera
- Thank-you gift for store employee(s)
One month prior: Send out your own press releases, including cover flats.
Know the answers to the most frequently-asked questions: “Where are the bathrooms?” (“Right over there”) and “How much did you pay to get published?” (“Nothing. I don’t pay publishers; publishers pay me.”)
Arrive early.
Smile. Regardless.
* Candies are individually wrapped; e.g Hershey Kisses, Andes Mints, Starbursts, etc.
JAMES D. MACDONALD 
Needless to say, you don’t put all of these things out there on the table. The bookstore itself may provide all, most, or some of them . . . but if you find yourself at a scheduled two or three hour signing in a bookstore that doesn’t have an extra chair, you’ll be grateful that you thought to bring one along.
And be kind to the bookstore owners, even if they did forget that chair. If they have cause to remember you fondly, they’ll be more likely to hand-sell your books to interested readers even when you aren’t there.