I used to keep my fabrics sorted by color in separate clear containers, but the system broke down, mostly due to my general flightiness. Now I stack them in no particular order in plastic drawers so that they're easy to spot and easy to get at, and quick to put back. I usually do scrappy quilts, and I find the odd mixture more inspiring. I'm sure my "system" would drive most organized people bonkers. When I get some particular thing in my head and can't find it, that does get annoying, but it doesn't happen very often. I don't keep a very big stash these days. It's more useful to me to shop when I know what I'm looking for and how much I need, and anyway, I've reached the end of my available space. Quiltville.com has some valuable pointers about the stash.