I write a 1-2 page requirements document (and closer to 1, never more than 2). It tends to have two major parts: broad descriptions of what the system will do and very specific "must have" goals (e.g. transactions/second, max users, as well as functional ones; whatever makes sense).
Enough to keep in your mind for the rest of the project. It's a great organizer (I suppose the first is sort of a mission statement without the buzzword bingo), but again, for it to work it must be very short.
As far as ritual (and it helps that I'm starting a new project right now), I do play a certain type of ... determined music when starting. Archetypal for me is soundtracks of anime combat series e.g. Gundam UC (Zeta, CCA, F91 (Victory tends to be a little too depressing) and lately SEED. There are other titles (oh, the New World Symphony as used by Boring Germans in Space (LOGH) for the "empire strikes back" bit), but what they have in common is that my mind associates them with certain types of action. Certain ballet music works well too (my sister danced so I got into that genre well before college).
(Note, though, that I've been big on soundtrack music since a teenager, a bit before I was doing this sort of thing just after exiting my teens.)