I use an old CD organizer to hold smaller amounts of fabric (1 yd or less) up in my sewing room. Larger amounts of fabric are folded similar to how they look in the store on the bolts, but don't have the cardboard inside (more space for fabric that way), and are kept on the bottom shelf of my fabric cupboard! Medium amounts of fabric are folded to look like books and stand up in cupboard in relative ROYGBIV order. All fabric is easily accessible.
All flannel is folded similar to larger pieces of 100% cotton fabric and in shelving unit in closet in sewing room, or precut into 10" pieces ready for the next rag quilt I make!