How to Become an Overnight Success
Pure pig-headed determination has a lot to do with it. While I'd been puttering with stories for years and only showing the results to my close friends, once I finally took the notion that I could actually sell my scribblings, it took me another four years of half-hearted and half-witted marketing to make my first "sale," to a regional magazine that paid in contributor's copies.
With that stunning success under my belt, I got semi-serious, and while I continued to place pieces in minor markets now and then and receive ever more encouraging rejection letters from the pros, it still took me another four years to make my first professional sale.
Wow, I was on a roll now! After that story hit print (a year after it was accepted), it took me another two years or so to reach the point where I was selling most of the short fiction I wrote, and another three years after that to sell my first novel. So by the time I sold Headcrash in 1994, I'd already been trying for fifteen years and publishing professionally for ten, and it just cracked me up every time some clueless reviewer made reference to my being a "new" writer who'd "come out of nowhere."
Overnight success rarely happens overnight. While there have been a few cases of writers scoring big with their first stories, most writers I know have a whole box full of awful and unsalvageable early work squirreled away somewhere and face at least two counts of Attempted Novel.