A good book title stands out, tells readers what the book is about, and is not already taken by another book. Its length matters less than you might think.
So you have written your new book, or at least most of it, and now it is time to think about the title. How do you go about it? Here is a simple guide, in three steps.
1. Make it stand out
Some experienced writers advise you to keep a book title under five words. That is not a rule you have to follow. A title can be a single word or a whole sentence. Length is secondary here, and in some cases it does not matter at all.
Take Everything I Know About Zombies, I Learned in Kindergarten by Kevin Wayne Williams as an example. That is a catchy title if you ever saw one.
Is it too long for a title? Maybe, but it is catchy all the same. In a stack of post-apocalyptic zombie novels, this title stands out nicely. Will it also be memorable? You can bet it will.
2. Make it descriptive
Your title should name the most important thing in your book. The Harry Potter series is a perfect example: the title of each of the seven books clearly names the one thing that the book revolves around.
What about book 4, Harry Potter and the Goblet of Fire? J.K. Rowling could have called it Harry Potter and the Triwizard Tournament to make it more descriptive, and she did consider that title. (The working title was Harry Potter and the Doomspell Tournament.) She settled on Goblet of Fire because, in her words, it has "that kind of cup of destiny feel about it", which is the theme of the book. So a title can describe the theme of a book as well as its plot.
3. Avoid duplicates
A duplicate title is easy to avoid. When you come up with a good title, search for it online. If no other book uses it, it can be yours. That is definitely easier than choosing a username for a social media account, where every smart and funny name you can think of seems to be taken already.
In the same vein, avoid a title that is too similar to the title of a badly received book. Search an online bookstore for your planned title and see what comes up. You do not want readers to link your precious work with a book that got poor ratings.
Many of the rules for a perfect headline apply to a book title too. And if you are still working on the book itself, read how to write your own book.