Mostly by color. Batiks, Christmas prints, solids, 1930s, homespun plaids and vintage are my other categories. You have to do what makes sense to you.

I think the best approach to organizing stash is to figure out how you work, then design the system to support your work style.

I've tried many systems of organizing and the one I have used for many years (about 12) is a cubicle storage system in a closet. I work predominantly by color, so I organize by color. My fabrics are sorted by one color per cube with the exception of a few specialty stacks on a shelf - ie. 30's, batiks, solids. All sizes of one color go into one cube - yardage on the bottom, smaller pieces in a basket on top. There are also a few cubes with UFO's and WIP's - in boxes and clearly labeled.

When I want to work with reds, I pull the whole red stack and basket out of the cube and set them on a table. If I want to include reds from the specialty stacks, they are easy to find.

I generally sort by color but keep solids separate. If it is at least 1/4 yard or bigger. Anything less than 1/4 yard is in a scrap bin but also sorted by color.

I like mine all done by color. I don't really have any holiday fabrics. Yet. Lol

Solids - Sorted by color on shelf
Christmas - Tote
Other Holidays - Tote
Panels - Tote
Fat Quarters - Sorted by color in small totes
Yardage - Sorted by dominant color on re-purposed DVD shelves
Scraps ( anything smaller than a FQ ) - get cut into strips and sorted by width of strip in small stacking plastic drawers
Charm Packs - drawer
Jelly Rolls ( purchased, not my 2 1/2 inch scrap strips ) - Small tote

Yes, I am a tad OCD LOL, so my room tends to be organized even when its a mess !

I have plastic boxes for colors and then one for Christmas, fall, children, batik and 30 vintage. Then one for patriotic.
Before i use to put projects and their fabric together, but found the solid fabrics needed to be with their color box.
so I did not buy more of that color.
happy organizing and labeling. In the end" have it your way".

I organize by color excluding stripes, flannels and collections. Those I try to keep together. Oh yes, kiddie fabrics are usually separate too. Guess that's not much by color is it now???? Anyway, most are by color, on comic book boards or if more than 5 yds., I have them on bolts. Fat quarters are by colors in plastic shoebox size totes and scrapes are by size. When it doesn't fit the comic book board, it becomes a fat quarter or scrap.

I have a dwindling stash because I used it to make tote bags for Christmas. (10 all together). But, found that I can
re-purpose those plastic boxes that salad mixes come in. They are clear and they stack. I have them arranged on the
shelf in the closest, by color, holiday or fabric line. Not only, out of the way, but looks pretty too. I never had a huge stash to begin with, but this is working for me so far.

In order to fins what you need in the future, you need to organize what makes sense to you. Read all the suggestions, then pick one the goes "ah ha!". That's the one.

Smaller than a yard is sorted by color, in an eight drawer dresser, larger pieces are in another cupboard, not sorted because I tend to buy these as needed or find at rummage sales, fleece in one huge tote, pre-quilted in another huge tote, faux fur and flannel has it's own cabinet, patterns, trims, and closures, on a shelf in this cabinet, thread in an old thread holder, rulers on a nail (but looking for a better idea), liquid supplies on a old set of library shelves, batting on top of faux fur closet, and all polyester or non-cotton fabric stored in a huge antique horribly painted (several times) solid oak dresser, with four 1 foot deep drawers, that was hand made sometime before grandma was born. I keep all collections and precuts in their own dresser. I like to sun proof all of my fabric, so drawers and cupboards are a must since I have a cloth shower curtain on the window for diffused light.