Reduce, reuse, and recycle! In a consumerist society, it can be difficult go for even a day without buying anything. When you do buy stuff, try to make sure it's stuff that will last a long time and can serve multiple purposes; avoid buying disposable items when possible. Also, consider the "greenness" of the company that made it! Before throwing anything away, try to find creative ways to reuse it. You'd be surprised what you can do with old Altoids tins, socks, plastic bags, plastic bottles, and, well, everything.