I have my fabrics washed and pressed and everything cut. Then, depending on the kind of quilt it is, I might make some units or sub-units, whatever will fit best with the least amount of folding in a plastic grocery bag, which I then store in boxes of a size that I can easily manage, about four or five kits to a box.
So for a quilt made of largish equilateral triangles, for example, I won't sew anything together, I'll just lay out the quilt on the wall, and take down the pieces in row order and label them. With a small piece quilt like a Bonnie Hunter quilt, I'll make the units that constitute a block. I started doing this at first because I was impatient to get my stash organized, but I recently realized it's also a great way to have a supply of leader/ender projects on hand.