I attended a writing workshop recently and started re-reading two books on mystery writing that I picked up a while back. While there are a ton of books out there for the would be novel writer, many are cliché filled ("write what you know") from writers who seem to specialize in how to books rather than novels anyone would want to read. These two stand out as being tailored to mystery writers and are written by successful novelists.
James N Frey wrote several popular novels in years gone by, but then began focusing more on the craft of story telling. He has written a slew of books on how to write a "damn good" novel. While they are all good, you really only need one of his books, whether it's this one or the original in the series. Frey focuses on the story behind the story to help you uncover the motivations of the characters.
Similarly, Robert Ray wrote a book called "The Weekend Novelist" and then later a more specialized one on mystery writing. Note that if you buy the original book, the first edition with a yellow cover and no co-author gets much better reviews than subsequent editions. One nice thing in this book is that they dissect two popular books in the genre, one by Agatha Christie and one by Martin Cruz Smith. Even if you have not read these book, it provides practical examples of the techniques. Ray also provides a 52 week schedule which enables you to, at least in theory, complete your opus in a year.
Both books are available from Amazon in print and in Kindle editions. If you have other recommended books on fiction writing, please let me know by adding a comment below.