How you organize depends on how your mind works
You've come to the right place for suggestions, and will certainly find something that works for you.
I tend to buy with specific projects in mind, so most of my stash is organized per project. Leftovers and "impulse" buys are organized by floral/dominant color, print, or color. It's not really as "organized" as it sounds, but that's my excuse for opening all my tubs and wallowing in my fabrics on occasion.