A quilt appraiser taught me this: use the strips of batting for storing quilts. When I am folding the quilt, I put batting strips where the fold is. This makes a rounded fold rather than one that gets squashed down and makes a crease in the quilt.
You only need to bat the first few folds, after that the quilt is thick enough that the folds won't squash down.
I have quite a few quilts that are folded and this is a great method. I also take them out every few months and fold them differently (with batting) to even-out the pressure on the fabric.