I don't have any organized system for storing, just throw them together. As for size, I keep anything that will accommodate quarter inch seams on all sides and still leave fabric left to see...my no-brainer sewing is making new fabric by just piecing together any of the scraps in the bag. When I want to make a purse/tote/apron, etc., I often go to this scrappy fabric first. If it's too scrappy, I add a solid color to it to highlight the fabric.