Everyone has their own way of writing. I don't mean style, mind you, but the actual process. A lot of us are plotters, who plan the story to varying degrees before actually beginning to write. Others are "pantsers", who sit down to a blank page/screen and start writing, and just see where the story or their characters take them. That's also not exactly what I'm thinking about.
I'm talking about when you finally sit down, where are you? What has to be in place?

I remember reading Stephen King's Misery, then watching the film (not sure whether the axe or sledgehammer would have been worse, but I'll bet neither was pleasant). In the film, he had to have a glass of wine and one cigarette waiting for him when he finished his draft. That's the kind of particular I'm wondering about.
See, I can write as long as it's on a computer. My hands cramp (I have psoriatic arthritis) if I try to go at a blank page with a pen or pencil. But a keyboard works better for me.

The other thing is sound. I used to have to have complete silence. That's not so easy unless you live completely alone, and I love my wife and dogs more than my writing (by a long shot). So I tried listening to an iPod once.
It was a problem at first, because I kept singing along to the tunes. But as things went along, and I listened to the same playlist every time, I stopped humming along and eventually tuned it out all together.
Now I can't write well without it, which is a blessing and a curse.
So what about you guys? What little peccadilloes are involved in your process of physically putting butt-in-chair and writing?