I'm pretty much like Suz. I organize by large categories first; i.e., batiks, Christmas, Halloween, Easter, religious, flowers, trees, water, skies, animals, geometrics, stars, children's, wilderness, patriotic, etc. Then within each category, I subdivide into smaller groups if necessary; i.e., children's are divided into sports, toys, cars, etc. Each group and/or subgroup are organized by color.
I cut my scraps into 2" or 2-1/2" squares and segregate them in three bags: light, medium or dark. My 1-1/2" or 2" strips are stored in a bin
I can usually find everything as long as I don't let my stash get out of control and I put everything back after finishing a project. It also helps to keep my quilt room neat if I cut my squares and strips as soon as possible before my scrap pile becomes the 800-pound gorilla in the room.