My recipe of writing:

1. Inspiration - it is the mood cultivated to get you started and also a sparkling moment that you think you should write;
2. Undecided length of time for the pre-writing brainstorming session, during which I never write things down and I tend to remember the details and the flow in my head. If I forget it, just let it be forgotten as it's never the crucial part;
3. A bit horniness - not so horny that you need to get laid right away, but a bit of horniness would give me a sense of urgency to set goals and make things finish;
4. A noiseless, but not quiet environment - contradictory, I know. I take voices as the okay sounds but noises as the vice;
5. Zero disturbance - I could multitask but it's hard to tell exactly what I could and couldn't do. I could msn with (some) people upon writing, but can't with others. I draw boundaries inside my head and make them happen in real life.