I warmly second the recommendation to read Fletcher. Complete Walker IV (co-authored with Chip Rawlings) is the most current, and contains the most information about packing light. Complete Walker III, written by Fletcher only, is probably the best written - but packing light was just coming into fashion, and the gear makers weren't offering light gear yet (and cottage makers were just starting to spring up.

Fletcher talks about the feel-how, not just the know-how. I learned to backpack using the original Complete Walker.