You have your first novel in mind and all you want to do is buy truckloads of books on writing.
I know you're excited but put the books down and step away from the Writing Reference section.
If you start buying writing books with no clear direction you'd end up with some you'd never use. (I know. I have plenty.)
The first thing you should do is write your story. Don't worry about it being perfect. Like I said in Got Nuts! -Rough Drafts, the first draft is going to be garbage. Its purpose is to move the story from your head to the computer or paper.
So, do you buy the books after you've written the draft?
Have you read any books in your chosen genre? Reading what's already been done can teach you more than any writing book ever could. In every genre, there are books and authors that set the standard. For Dark Fantasy, it's books by Neil Gaiman and George R.R. Martin; for Horror, it's Stephen King, Edgar Allen Poe and Bram Stoker (to name a few). Find these giants for your genre and analyze them. Make notes in the margin. (Reading like a writer deserves its own post. I'll get into that next time.) Don't just read books in your genre, every story can teach you something.
If you've done this already, examine your story in comparison to what published authors have written. Do you notice an aspect of your story is lacking? For instance, are you characters flat, is your dialogue a bit weak, can your descriptions be better? Whenever trouble you're having, buy a book covering that subject. I usually go to Writer's Digest Shop, find a book I need then search for it on Amazon.com to see what others said about it. If the book got bad reviews, I look at the section called "Customers Who Bought this Item also Bought" to find similar books.
You should try finding the books you want in the library before you buy them, though. I have books I don't use anymore simply because I no longer need them. When I first started writing, my characters were flat and unemotional so I bought books on the subject. They helped me out a lot. I now have no problem making my characters come alive which means I no longer use those books.
Also, in almost every genre there's a book dedicated to how to write in that genre. For Horror, it's On Writing Horror by the Horror Writers Association; for Fantasy, there's The Writer's Digest Guide to Science Fiction & Fantasy by Orson Scott Card, Terry Brooks and many others. Find yours and buy it if you can, it will definitely come in handy.
Good Luck and Have Fun!