Divying up contexts is a great help, and ads a very useful granularity to any contexts that still leave you wondering precisely when you'd 'prefer' to do a particular task.

As BevvyB mentions, the 'booking yourself in' idea is essential for those of us who've forgotten the discipline offered to us (years ago) by the dreaded 'school timetable'.

Its all too easy to ignore contexts sometimes - opting to do something far less like work for instance, or even nothing! - so being told by your stricter self that you'll be in a position to tackle a certain context at a certain time in the future is a great help. Not having a P.A. or a nagging wife, I set repeating calendar items just for this purpose and it feels like I have a helpful assistant directing my week for me. Certainly stops me sliding into that slack state.
I currently have google Calendar popups / txtmsgs / emailreminders doing the job of keeping me on a schedule when I need it, but I must say I like the idea of automating iCal to open OF perspectives.