There's a few dozen how to write books out there and many are worth your time, some aren't.
Don't let the rules restrict you. But learn the rules, know the rules, so you're aware you're breaking them. Rules are there to be broken, but they're also there for a reason.
Stephen King talks a lot about adverbs and how they shouldn't be used, but Stephen King uses adverbs in all of his books. It's definitely better to write, she runs, than to write she walks quickly.
However, sometimes, adverbs matter.
Which is why I personally find it important that as a writer you read about the craft, and learn what works for others.
On the other hand, don't be afraid to figure out your own process, your own style, and your own voice. When I first read "On Writing" and other books, I ended up stifling myself. A desperate attempt to follow all rules and produce quality writing. I blocked myself. I suffocated myself.
Don't let the books keep you from writing. Write, write, write. Read, read, read. Those are the two things that will improve your craft.
If you like King's work and write, give On Writing a try. I felt like the man spoke to me, and it is a book I treasure to this day.
Invisible Ink and Story are two books that taught me a lot about structure and how to build a story from scratch. They both talk about themes, messages, reveals, plot structure etc. They're geared towards screenwriters, but I found the advice invaluable.
In fact, if I were only allowed two books about writing, I'd probably choose these two books.
Honorable mentions for two books I thought were helpful, but that I've not yet been able to fully incorporate into my process. Take Off Your Pants teaches you how to outline. I am really bad at outlining, I mostly write organically, and just go with the flow...but I try. And 2,000 to 10,000 teaches you how to write faster but better at the same time. Only, it involves plotting and outlining, and as we've just established, I'm bad at both.
However, I'd still recommend these books to a beginner. Much of the info in those two books are probably known to people who have been writing for years.
If you're thinking about self-publishing then this book teaches you the basics, but it also quite simply reveals that the most important part of the process is to write, write, write. Oh and also: work, work, work.
NaNoWriMo is around the corner. Who is with me?
What books on writing would you recommend? Let me know in the comments.