Admittedly, my stash is small, but I organize fabric by color and size. If I have purchased fabrics specifically for a project that has not yet started, I put the fabrics, pattern and thread in a plastic bin of their own, so everything is together when I am ready to start. I like it by color because that is often what I am thinking about when I am combing through my stuff -- trying to pick a specific color to go with something. Hope that helps!