I usually have a pattern in mind that I am going to make in the future and I pick up the fabric for that pattern as I see it. Usually, I haven't written down how much of each fabric I need and I end up with too much. Need to change that.
Sometimes I see something I love and I'll buy 2 yards (metres). But, that doesn't happen too often and those fabrics often sit on the shelf because I like them too much to cut them up. (Figure that one out.)
My current plan is to start picking up solids because that is something I don't have a lot of, so I'm going to write up a plan and start filling holes in my stash.
Because I do collage, if I see a really neat patterned fat quarter that I think I could get a lot out of , I'll pick it up.
I will buy whites and blacks in larger quantities if they are on a good deal because I seem to go through those quickly, but I try to always buy the same company/product so I know the scraps I have hanging around are going to be all the same shade, more or less so I can use them all together. (As in, always buy Kona White, for example.)
Watson