Yay, What's Your Process is here!
And I have to say, my process varies a fair bit. Obviously I come up with the idea first. Usually it's a character, not a place or a scenario. For instance, with SQUEAKY MCLEAN, I was at work one day, and I made a mouse-like squeaking sound. So the character Squeaky McLean was born. And with SUNDOWN, I thought about my ideal man (as opposed to the apparent ideal man to many at the time, Edward Cullen) and came up with my beloved Jared. A kind-hearted, tall dark & not-quite-handsome rock star. Can't get much sexier than that. :D So yeah, it's usually a character I will come up with first. Not always their name, but their face and demeanour at least. And often, I will indeed see the situation they're in at that point too. But for Squeaky and Jared, it was just the face, and their role in life.
The rest of it goes from there.
But wait...this wasn't about "Where do you start?" it was "What's your process?"
1. Think of a character, and what they're about.
2. Think of a scenario that character would likely find themselves in.
3. Start writing.
I don't necessarily plan my stories out. I did that with NaNoWriMo 2010, and it certain helped me stay focused, but (and I'm not sure if this was coincidence or not) I also found the novel quite hard to finish. Once I got past 50k, I really slacked off and found it a bit of a chore to keep writing. I'm not saying this is because I planned it all out. But it may have some relevance.
I admit that with SUNDOWN and the other novels in that series, I had to do a bit of planning. Namely, a timeline. A very extensive timeline. And I've referred to it constantly throughout the writing/editing process. It's been essential. So I guess that counts as planning it all out, right? Then again, the timeline underwent serious changes here and there as I changed my mind about things. I even did an "alternative timeline if so and so hadn't died in book 2", so that the characters would be able to refer to where they would have been if not for the death.
So yeah...I guess that's my process.