I sort by color. Pepper Cory, a nationally known quilter, says she sorts by dark, medium, and light. To each his own!

When my DH first built me a very large cabinet for my stash I organized by color, then I moved fabric around and put fabric that when with other fabric together--now I have 8 shelves of assorted mess... I pull out something to use, change my mind and shove the fabric wherever I can find a spot.
My best fabrics--from Italy and Japan, I keep in a special container and take them out once in a while and pet them and then put them back to rest.

What organisation?

Ha ha ha ha ha!! ROFL. Organize fabric! Too funny!

Really, though, I started re-organizing this weekend. I bout 16inch tubs at walmart and I have them organized by theme of fabric, 1 or 2 projects in a tub, and scraps. Using clear tubs so I can see what's in there.

Color, pattern, size and texture

i sort by color and then a seperate for holiday fabric

I have 2 of the cube storage units that DH and I got at Target. Each cube is sorted by color. Though I do have one spot for batiks (only just starting to get into them) and another has winter themed fabric. I have 1 huge plastic tote that has my flannel and other "different" fabric, velvets and corderoy.

I sort by collections, specialties (Christmas, flannels, minkee etc.) then by colors (ROY G BIV).

Me too.

I cannot lie. Sometimes (like right now) mine looks like this. I keep wishing for the good fairies to sweep in and organize it all but alas I have to do it myself. Then as soon as a pull out stuff for a couple of quilts it is back to a mess.