telling course that got me started. Then I began writing, taking more English classes, including Brandon Sanderson's class just before he really became famous. By the time I took his class, I'd already written three novels.
I generally map out my characters and outlines before I start my novels to see how much of an idea I really have. If I can get a full interesting outline with good character and story arcs, I write it. Then I take a break for a few weeks or even months, then rewrite and edit them. Once I feel like it's ready to share, I send it to beta readers to critique. Then I rewrite/edit 1-2 more times. Then I get serious about publishing it.