There’s been quite a lot of talk in the Web design community regarding the organization of long, unruly stylesheets. Good points have been made by most of CSS’s talking heads, with Douglas Bowman’s Stopdesign article receiving the most link-worthy praise: see CSS Organization Tip 1: Flags.
Honestly, as it is no longer 2003, or 2005, or whatever year you consider to be the latent awakening of popular CSS usage, these rules of organization - moreover these helpful tips – can largely be considered givens rather than guidelines { Full Entry }