One of the greenest as well as money-savvy things a person can do is browse a yard / moving sale. If you find an item worth purchasing you are helping declutter another person's life as well as enriching your own by getting items at a steep discount (especially if you bargain!) Where else can you buy an entire knife collection for five bucks?!?! Or a coffee table for 90% off of the original retail value? Another person's trash can be your treasure.
The key is to cruise around the more affluent neighborhoods in your area, as their accumulation of "stuff" tends to match their lifestyle (Pro Tip: sometimes they are called estate sales, so bundle those into your yard sale search).
Not all yard sales are winners, but moving sales usually are because larger items are the first to go. Paying to move large items is usually a pain or pricey. If you are in need of a dresser or larger items and don't have a truck or other vehicle that can fit it, ask a friend who does to lend a hand. If not, the sellers may be inclined to help at a higher price point on the item (bundling things like shipping and a ton of items is a double-edge sword that I stay away from until the very end).
Whenever I'm out on the weekend I keep a list of things I know I want to get someday but don't need to spend full retail price on, and when I check out a yard sale I refresh my memory (so you don't get stuff you already have or other unnecessary items).
What was your biggest score at a yard sale? Any tips and tricks of your own? Happy hunting!