Ann Whitford Paul gives great tips for choosing a book title in WRITING PICTURE BOOKS. I think the tips work equally well for novels.
While not every title will contain all of the characteristics, these tips are a smart place to start in evaluating possible choices. Is your title...
1. Brief
2. Catchy
3. Unique
4. Straightforward
Does it...
5. Express the Mood of the Book
6. Hint at What the Book Is About
7. Create Suspense
8. Give the Artist an Idea for the Cover Illustration
9. Include the Main Character's Name
10. Use a Catchy Line From Your Manuscript
Make sure...
11. The Title Doesn't Give Away the Ending
12. That A Child Can Easily Say It Out Loud (for picture books)
I compiled a list of possible titles and several of my critique buddies made suggestions. I used Ann Whitford Paul's book to evaluate the choices. I selected WHEN SARAH WASN'T LOOKING because it's unique. A quick check of Amazon.com shows me that it hasn't been used before. That's important because I want readers to be able to find my book without searching too hard. WHEN SARAH WASN'T LOOKING also delivers on #'s 5, 6, 7, 8, 9, and 11.
All in all I think it's a great title choice. Thanks to my friend Barbara Krasner for suggesting it.