Can anyone give me some general advice on how to keep css style sheets more organised?

I bought a reputable book on css about 4 years ago and after a while found that my css would get totally unorganised. This mean't that if I started a new web-site then I was afraid to use the same css style sheets in case I found it too difficult to alter the styling or layout.

I've now just picked a beginners book at my local library (published in 2009) on css which explains about how to use css style sheet and then use the @import directives in order to use multiple external style sheets.

Does anyone else use the @import directive to help organise their websites or is there an even better way now that I should know about?

Kind Regards

p.s I'm going to experiment with the @import directive at the weekend but I'm feeling a lot more confident already about laying out a website now.