I can only write on a computer. I have a fairly fast typing speed so I can keep up (more or less) with my thoughts. My handwriting quickly becomes hieroglyphics which is fairly unhelpful if I'm experiencing a creative burst.
I cannot write if there are other people in the room. It's impossible. I don't like the feeling of someone peering over my shoulder and seeing the words appear on the screen. I am a harsh enough judge of my work and any words of encouragement usually fall on deaf ears. I have said to my family that they're in a lose-lose situation. Criticism at an early stage is not encouraged and praise will be disbelieved since my thinking is that they have to say something nice.
Music? Only classical and only if I'm writing casually. If I'm under a deadline or the words are really flowing (what unspeakable joy) then silence is a must. I also am a writer-mutterer especially when it comes to dialogue. I mutter what I write and at the same time add editorial comments. This also may be another reason why I have to write alone - I'm not eager for other's to view my performance!
Before the writing? Emails must be checked and answered. Blogs must be enjoyed! A few games of Freecell never hurt anyone! If today's job is research then the internet is trolled. Pictures are captured. Time to sit back, turn up the radio and absorb my new knowledge. How can I use it? Can I use it? The self-knowledge of recognising that I'm looking up something for my own interest and nothing really to do with the WIP can be somewhat shattering but is ruefully acknowledged.
What are your routines? Are you one of these lucky creatures that can write anytime, anywhere? Must you (like some writers I know) write the first draft by hand and transfer it to computer as a second draft? I'm curious. Share your routines!