The first thing to do is figure out the width and depth of your shelves. Most shelves are a standard size - mine are 30" wide. The narrow shelves are just over 14" wide. The depth is 10 1/2". You will want to fold your fabric so you can get the maximum amount of fabric on one shelf with little or no room left over. A little math, or some trial and error if you prefer, will tell you how to fold your fabric. I fold large pieces - 1/2 yard and more - one way, and fat quarters and smaller pieces another way. I almost always buy fabric in increments of 1/4 yard rather than eights or thirds, as these increments fold the best using my system. You can certainly modify it if you buy fabric in other increments.
Half yard and larger pieces:
Fold the fabric as it came off the bolt. I prewash and iron first - I find that ironing each piece helps set the colors and patterns in my memory - so I iron it folded as if it just came off the bolt.
Now bring the folded edge to the selvage edge for a second fold parallel to the first. I do this for 3 yard and shorter pieces. If the piece is longer than 3 yards I fold crosswise once, twice or more first.
Now, if you have an even number of yards fold the piece in half crosswise, and then in half again। If you have 3, 6 or 9 yards fold in thirds and then in half. If you have a different number of yards you will need to adjust your crosswise folds at some point.
The object is to finish with a rectangle that measures about 10" or 11" wide - or 1/4 the width of the fabric, and a depth of 9" (1/4 yard).
There are two possible ways to fold fat quarters. Choose which works best for you by measuring the depth of your shelves. If they are 12" deep you can choose the narrower, deeper way of folding - this is how I folded them before my sewing room redo. If they are less than 12" you will need to choose the wider, less deep way of folding so they don't hang off the front of the shelves. I show both methods in the pictures.
Lay your fabric in front of you. For deeper shelves the 21"-22" side should be facing you. For narrower shelves the shorter side should be facing you. Fold the closest and the farthest edged to the middle, thus enclosing the raw edge in the fold.
Fold again in half.
Now fold in half crosswise once. Your piece will now measure approximately 5" x 9" or 4 1/2" x 11", depending on how you have folded it. The second is preferable if your shelves are deep enough as you can get more fabric on the shelf.
Now arrange your folded fabric on your shelf, with the single fold of each piece facing toward you. ( I fold my towels and wash cloths so single folds face front also - I know, I'm an incurable neat freak!) I can fit two stacks of the larger pieces and one stack of the smaller pieces on each wide shelf - or one large and four small stacks - or six small stacks. I can fit two fat quarter stacks or one larger stack on the narrower shelves, with a few inches remaining for books, patterns, or whatever.
Since I do mostly scrap piecing and appliqué, I usually cut only a small amount from each piece. As long as I can refold the piece on the fold lines so it fits neatly back on the shelf I do so. Once the piece is chopped up enough that I can no longer fold it neatly on the fold lines, I call it scrap, and cut it into strips, squares, triangles and bricks, with the smallest parts going into a basket of crumbs to give away to a friend.
I hope this helps at least one or two of you with your fabric storage! I've done it this way for so long that I can fold fabric VERY quickly for storage on the shelves.