Think of ways you can reuse things you're about to throw in the trash. I often keep cookie tins and egg cartons. I also keep (and wash) meat trays and oatmeal containers. Meat trays make great paint palettes. I cover oatmeal containers and use them to store pens and pencils on my desk. In fact I have two that I made sitting on my desk right now!
Use Pinterest to find interesting ways to reuse some of the things you have laying around your house. Earth will thank you!