How I sort mine:
First, solids from prints, in fact, they're on different floors of the house!
The prints:
by main color BUT certain collections have their own shelf:
1. sewing theme
2. dog
3. animals
4. 30's prints
5 juvenile
6. patriotic
7. gingham
8. Christmas
9. Other holidays
10. Bugs
11. prints of shoes
12. lightweight denim-looking fabric
13. Hawaiian prints
14. fabrics that I bought as a group - they were next to each other at the store, and meant to 'go' together
15.African animal prints - due to my many basenji themed quilts
16 polka dots
17. Alaska theme
18. plaids
I'm sure there are others (those are only what I can recall from memory), and that list alone makes me realize it's not really an organized stash, is it?