M. Scott Snelten
First, there is no one, single path to becoming a writer. There are so many different, valid paths. It takes humility, ardent passion and untold patience to find your way. I am weary of anyone who says "It's easy."
In the early stages, I had no clue how to become a writer; however, I knew that I loved renowned writers like Dante Alighieri and John Milton, and, of course, Dan Brown (who has his own way of adding a classic touch to a modern tale).
I read a lot of how-to books. Unfortunately many of them were garbage. I know that's harsh language, but I'm being honest. In terms of writing structure, I really benefitted from reading The First 50 Pages by Jeff Gerke, The Writer's Journey by Christopher Vogler, the topic of the hero's journey from Joseph Campbell, and the topic of plotting a six-stage screenplay structure from Michael Hauge.
Additionally, writers need to familiarize themselves with the terms of the business. One super-informative book is Business for Authors: How to Be an Author Entrepreneur by Joanna Penn. It answers practically every question--you never even knew to ask.
As you may have figured out by now, a writer must consider the art, structure and business of writing. It's a lot of work, but the passion to be a writer and tell meaningful stories carries you through.