I usually sort by dominant color. So pink with white dots would go in the pink pile.

The largest portion of my stash is on open book cases. The windows are UV protected and face north. The shelves are filled with 1/4 - 1yd pieces, folded into a size no larger than 5 x 9". The 5" side is on the "book spine" side of the shelf and has a fold to easily see the fabric. There are 5 stacks on each shelf. They are divided into sections: solids, looks like hand dye, christmas, multicolor, oriental, black & white, flesh tone, stripes, browns, greys, silk, 30's, and the rainbow (red, orange, yellow, green blue, purple). When a type of fabric will make 2 stacks, it gets seperated out. Projects in progress are in "ArtBin" totes, so there's fabric in them too. And "thinking about it" is stacked anywhere there's a flat surface. As you can see, my system is morphic- it changes with what I'm working on. UFO's: probably 40+ are hung in the closet, in ArtBin totes, in drawers, on the design wall; I give myself permission to put something aside that has me stumped or there's a deadline for something else. It's not a job, it's a passion. Large pieces are stored in the hall closets. As my style of quilting has changed and become more defined, my stash has changed.

Lots of great ideas here - I also use many of them. Sort by era (30s, civil war, etc) color and size - all big enough for backing a quilt is stored in one place.

Background color is what i use.

I do what most have suggested...keep in themes, but I also have Large quantity pieces that I might use for a backing in one location.

I also have landscape type fabrics together since I do a lot of applique and often need grass or water...etc. I have several plastic drawers filled with small quantities sorted by color for applique use also.

This is a problem I think we all have. We all have different solutions as you can see. A lot depends on space as well of fabric theme or color. Now that I have a whole room, although a small one it is easier for me now. I have a lot of furniture in my quilt room that is recycled. I have two tall book cases with adjustable shelves. On those I have fabric and two shelves of quilting books. If you ask at Joanns of your local quilt shop they will probably be happy to give you the empty cardboards that the bolts are wrapped on. I cut them with an exacto knife so I have one thickness of width by 11 1/2 inches. You can get at least four from one board. I wrap yardage on them and stand them up on the shelves by color. Fat quarters and scraps are in clear shoe box size bins from dollar tree by color. I do keep my holiday, civil war, and 1930s fabrics seperate, but using the same system. I have another book case that I keep the totes on. My machine is on a used desk with some drawers I keep small notions in, all that stuff you had to have that you don't really need at all. The best thing was wrapping the fabric on the cardboards, the stacking always ended up in an untidy mess.

I have 8 of those 32-gallon clear storage bins and 6 smaller bins plus 6 of the decorative oversized hatbox type containers, on a couple of chrome storage racks from Home Depot. They slide out easily, heavier ones toward the bottom. I sort by flannel, children's flannel, terrycloth, chenille, novelty, 30's, holiday, batik, cotton, and project. I have two large bins of gallon-size plastic bags containing leftover fabric by project. That doesn't work too well, but I've yet to figure out a better way. So I inevitably pull out a bin and sort it on a cutting table to get ideas. I also try to buy all or most of the fabric for a project at one time, especially when it's a specific line, and those go in bins and boxes by themselves. Overall it works well enough, since I don't need to rummage too much. I am collecting chenille for a baby quilt (with minkee on the back! So soft!) snd am a fat quarter-fanatic, so i wind up with ;ots of uncategorizable stuf. Have tried putting all the blue, green, etc. in their own bags, but then I come to the jelly rolls, and they pretty much have to stay together by roll. Then I sometimes have larger amounts (like a yard or more) left after a quilt, but there aren't enough of those to really categorize, so I keep the projects together, in case I want to make a two-patch for a pillow sham (haven't yet, but I might!) I think there is more heart/soul than brain involved in my sorting. I believe that, as long as you can find what you need in under a minute, you're organized enough, no matter what it looks like. And quilting is a very artistic, creative pastime, so I get lots of ideas from random bits of fabric that appear next to something unrelated.

Sounds like a great way to me!
Country1

I sometimes struggle with the sorting of fabrics.

What I found that works best for ME is to look at the background
color, is it predominate over any other color? if yes then I put it into
that pile (predominately black background goes into the black pile etc.).

If there is a variety of colors in equal or close to equal amounts then
I put it with a "multi-color" pile, you would be surprised at how much
fabric I have in this pile.

Of course this might end up changing as I get going more with sorting
fabrics to share with my daughter who is beginning quilting. She doesn't
need to go to a fabric store to buy. All she has to do is go shopping at
"moms" place.

LOL

I sort calicoes and "regular" quilting fabrics by color with a few exceptions. I keep blacks/white; red/white; blue/white together. I keep my Thimbleberries separate (but haven't sub-sorted them by line). Other categories are Civil War fabrics, 30's fabrics, juvenile prints, panels, patriotic, seasonal/holidays, border prints, homespuns, neutrals. backings and shirtings (which are my newest "thing"). I'm still trying to come up with better organization with scraps. I keep fat quarters in a cd tower and scraps (depending on size) in drawers of an old bureau but really like things out where I can see them.