I have a habit of reading a lot of different types of books, but my non-fiction focuses on writing and business, for the most part. With that in mind, I thought it would be a good idea to recommend some books for writers, no matter what stage they're at. (Though, obviously, more established writers may find less benefit from these than relative newbies.)
1. Screenplay, by Syd Field
Not everyone will write a movie. Not everyone should write a movie. However, as far as stories go, getting a strong overview of how to write one for one medium is a good idea, so long as you're prepared to transfer the lessons to another. Syd Field's book is incredibly approachable, and it covers all aspects of writing a story. The actual screenplay aspect of the book is limited to particular chapters. The rest is applicable to writers generally, with exercises most books on writing fiction don't include at all.
2. The Millionaire Messenger, by Brendon Burchard
While I would consider it of greater benefit to someone writing a non-fiction book than it would be for a novelist, The Millionaire Messenger is an excellent way of ensuring you focus on the task at hand. It's an important book for understanding the value of your message, whatever it may be, and it can help inspire you towards greater things.
3. Write and Get Paid For It, by Terry Prone
The title alone is worth paying attention to, nevermind the how-to information in the book. Terry Prone's guide on how to earn money from writing is important for writers who actually want to do that, and while the most recent edition is before most of the major successes in self-publishing and ebook publishing, the advise is still applicable to writers today. (The last edition was published in 2010, but take it from someone who's been publishing for a couple of years, and from a long-time bookseller - it's now an "old" book.)
4. The Curve, by Nicholas Lovell
Not everyone believes the future is digital. That's a problem for those people. Nicholas Lovell reveals what he knows and believes about digital technology, "superfans" and the power of free in his book The Curve, published in October 2013. It's an important book for understanding the challenges you could well be facing in the future, and it's handy to be able to prepare for them now rather than waiting to respond to them as they happen.
5. Is There a Book in You?, by Alison Baverstock
Alison Baverstock has always been a go-to writer for me. She writes plainly (which is a plus - everyone can understand her!), and she writes about topics that are important for writers. This book, her first about writing, is a good tool for self-identity. Not only does it help address the issue for many people - whether or not they can write a book - it also provides tips from the pros about how to write. It's old, at this point, but it's still a useful book to read, especially if you're just starting out.
6. The Writer's And Artist's Yearbook
While you only technically need one or the other - the former being for the UK market, the latter for the US market - they're both incredibly handy to have at hand. Keep in mind they update annually. While older copies are good for finding listings, and for the advice articles inside, you need to be sure that (a) the agent or publisher is still in business and (b) that the contact details and editors listed are still current. If new copies are out of your budget (and the library doesn't have them in stock), a good Internet search should give you the answers you need.
7. Teach Yourself: *Insert preferred genre/form here* (e.g. Write a Play, Write a Novel, Write Children's Fiction, Write a Romance)
Some people wouldn't dare recommend Teach Yourself or For Dummies books, but I find them useful for getting down to the bare essentials of a writing style or genre. Pick one, and give it a read, but don't rely on it for everything. The most important thing is to find out how to do what you need to, or to uncover the tropes of your genre, and then to discover more about it all by writing. That's the best way to learn.
For marketing advice... go to Seth Godin.
For life-hack advice... go to Timothy Ferriss, Chris Guillebeau, and Niall Harbison.
For my books on writing... click here.