Every writer has their own process for taking their idea and putting it on paper, and you will often come across some writers who are damned determined to tell you that their process, and theirs alone, is the correct process.
First, there is no such thing as one correct writing process, no matter the medium. I often view the varied ways a writer prepares their project in the same way athletes psych themselves up prior to a game, each with their own, sometimes strange, “good luck” rituals.
The truth is, the only correct writing process is the one that works best for the individual. In the end, no one will care how you got the words down; a studio isn’t going to drop an option because the writer failed to follow a specific outlining process. Any time you come across a writer who insists that “such-and-such” is the correct way to plan and outline a script, you can be sure it’s because that process works best for them, but that doesn’t mean it will work best for you.
So, I thought I would take a bit of time to explain my own writing process, as I have been asked a few times recently what that exactly entails. While this applies mostly to screenwriting, I have followed something very similar when I was working on my novel, so some of the ideas can be crossed over.