I basically have two modes: One is to do a writing stint each morning. It's the first thing I do after waking up. (Well, actually the second. Gotta make coffee first!). I just sit at the dining room table and crank while my brain is sharpest. I can usually write for an hour each morning, even when I have other projects going on.
My second mode is to dedicate entire days to writing. This is reserved for big projects, like the Sprint book, or finishing up an article. I'll start these days at the dining room table, like usual, but often change venues throughout the day—sit on the couch, go to the office, visit a café, etc.
I prefer to write in the morning. By 3pm or so, my energy and focus aren't so good. I use that time for other tasks.
For my morning stints, I can go up to 90 minutes without a break. But if I'm going to be writing all day, I like to work for 50 minutes and then take a break. In that routine I can get in about five hours per day. Five hours doesn't sound like a ton of work, but I'm actually pretty proud of that. There's some research by Anders Ericsson showing that the average person can't concentrate for more than four hours per day. Take that, average person!
I went to journalism school, where my professors drilled into me a very structured way of writing. I ALWAYS outline before drafting. The only exception is that sometimes, just sometimes, I get a very specific idea for how to open a piece, so I'll just jump into drafting that prose. But after I write the intro, I'll go back and outline the rest of the piece.
I start almost everything in Notes on my iPhone. Tweets, articles, book chapters, everything. I know that's weird, but it helps me get started because it doesn't feel like "real" writing. There's no pressure.
After a bit, I switch over to Notes on my Mac. When I have a complete (but rough) draft, I'll copy it into Google Docs and work there. I love working on manuscripts in Google Docs because it has revision history and really good collaboration features. Jake Knapp, my co-author on Sprint, is one of my colleagues at GV and my writing partner. I ask for his feedback on almost everything I write, and he does the same with me. Our skills and tendencies are very complementary. I'll send him the doc and he can make his notes and suggestions right there.
Ideally, I have just a few tabs open at one time. Google Calendar is the only tab I always keep open, but I like to close everything else, including email. If I'm writing I'll usually have a few tabs open with reference material.
John Zeratsky is a design partner at GV and the co-author of Sprint: How to Solve Big Problems and Test New Ideas in Just Five Days. Say hi to him on Twitter.