I have made labels to put on the fabric I buy. It tells me (when I write it on the line) When I bought it, how much I bought, how much it cost, what project it was bought for (if any), and if I can get more of it. (sometimes if bought at WM you can't get more). I also put on there what type fabric it is, and the color or print so I can make sure the correct label stays with the fabric. When I use some of it I adjust the amount of fabric in the bundle/fold.
----- I don't always stay up to date on the labels, but I try. It helps to know how much fabric is in the piece without unfolding it all the time to check if I have enough.