I was a reader and then the writing came naturally. Ideas flowed and the stories just had to be written. Now there are boxes of stories under my desk and in the closets. Maybe some under the bed, too.
Not all stories go anywhere. Some were just the start of an idea, but we put them aside and maybe someday....
So what, besides reading, is in a writer's tool box? First it has to be grammar. I like Stunk & White Elements of Style. It's a good basic book for grammar.
I used to recommend a good thesaurus and dictionary, too. However in the age of the personal PC, that stuff is now at your fingertips.
Aside from that a collection of basic information and writing books. Not every book will fit every writer. Look for character development books, one that will help you flesh out the people in your book. Just giving a character a name and description isn't enough. If you've ever done a character sketch you've learned that the more you know about your MC the easier it is to write their reactions, thoughts, and dialog.
Now, let's go to your genre. Is your book set in the present? The 1950's? Is it a story about where you live or a different area? Vampires? Crime?
Look to other more successful authors for the way they work their craft. I recommend Stephen King's On Writing and The Weekend Novelist. Both touch on the craft of writing and the discipline it takes to get things done. For without discipline where are we? Staring at half finished manuscripts and empty pages.
So, collect your books and make notes. Study your craft just as you would when you learn any other job.
Happy writing!