Crocheters store their yarn scraps in all manner of ways, from bags or containers stuffed in whatever closet has room to a variety of creative storage bins made from buckets, boxes, crates or totes. For maximum efficiency, easily accessible cubicle-style storage units make it much easier to sort, store and locate scrap yarn colors when needed. Plastic crates make great storage units; they come in a variety of sizes, stack easily on top of each other and are relatively inexpensive at discount department stores.
Before setting up your choice of yarn bins, be sure to select a wise location, preferably in an unobtrusive place in the living area of your home where it's cool, dry and clean. While you want the location to be handy for you, you do not want it to be accessible to pets and small children. Avoid places like an unfinished basement that can incur water leakage or mold, or a garage that houses dirty machinery, chemicals or little critters that might decide to nestle in or chew on your yarn.
Once you have selected a good location and set up your preferred type of storage-bin unit, you need to sort your yarn scraps by color and value. To help you see the colors more truly, lay them out on a white or neutral-color carpet or sheet. If you look at the color wheel below, you'll notice that the colors are arranged in "families" by value from lightest to darkest, so you should sort your yarn scraps in the same manner. Put each multicolored yarn in the pile with its predominant solid color. Put black, white, off-white and gray yarns in their own separate piles.
Once you have all of your color groups sorted, store them in the cubicles in whatever manner makes the most sense or is most workable for you. One way is to put the darkest-value shades of each color in the cubicles across the bottom row. Leave the column of cubicles on the right or left end free for the black, white, off-white and gray yarns.
In the corresponding cubicles across the next row, put the next darkest shade of each color, and so on with each row, ending with the lightest-value shades in the top row (similar to how the color groups are arranged on the color wheel). If you have only a small amount of several colors, they may be able to share cubicles.
With a small investment in time and effort and relatively low cost, you can have a well-organized system for efficiently locating specific colors in your leftover yarns when you need them. In addition, being able to view all those wonderful colors in various shades at a glance will be sure to inspire lots of crochet creativity when planning your projects!