Clearly, it helps to be in the right place at the right time, but it also helps to just do it. Showing up isn't half the game, it's the only way there's a game at all. So get that book out of the drawer & pop it on the Interwebs, people.
Oh, yeah, and edit the heck out of your writing:
My biggest word of advice to any new/future writers thinking about diving into Kindle: Edit. I don't care what you think, you didn't edit enough. Some people won't care that there's errors, its true, but enough of them will. And they paid for it, so they have a right to. So edit more. And then again. Really.