There's a book I'm reading that I love and HIGHLY recommend...
The One Hundred, by Nina Garcia (of Project Runway fame) is a must read for every woman who is the least bit interested in style and fashion. Seriously, I've made a note to self that this will be, from henceforth, the graduation gift I give not only to my own daughters, but to every young woman I know graduating from high school or college. (I would have loved to have this kind of information starting out in the big world of real life!)
I can't help but think of the enormously, pathetic amounts of money over my adult life that I've spent on trendy, spur of the moment purchases that I've greatly regretted after wards. Garcia certainly does not poo poo on trends...she loves them too, but encourages classic pieces that will always work with trends and without.
Read it for yourself. I think you'll love it!