The things that have worked best for me in reducing my stash are:
1. Limiting the amount of space that is available to store fabric. When it's full, I don't buy more until there is room.
2. Shopping my stash when I want to make a quilt- it helps that I like scrappy.
3. Thinking of my stash in terms of usefulness of the fabric for a wide variety of quilts. For that reason, my stash consists mostly of blenders and when I need to replenish it, I make a list of things I'm low on- for example- lights, darks, mediums, or specific colors. That's not to say I don't also have some really nice patterned fabrics, but they do not make up much of my stash.
4. Being willing to experiment with what I have on hand. After all, it's only fabric and thread- no one will be harmed if what I make ends up being truly ugly and I will still have had the fun of cutting fabric and stitching it back together. Any piece that is too ugly for words can always be cut up and turned into a collage quilt or an improvisational piece.
Rob