I will second the idea of purging materials you may never use. I have a small 16x20 garage/shop and I hate to throw out anything larger than a toothpick! I built a plywood storage rack that hugs one wall and holds about 8 full sheets, about the same thickness of cutoffs, and lots of small offcuts. Here is a sketch I did when I was making it. FYI, my ceiling height is less than 8 feet or I would probably have stood it up on end to save space.
It is attached to the wall with a hinge on the left so it can pivot out to make loading easier. I find that it helps to have a fixed amount of space available. If it doesn't fit here, I won't allow myself to keep it.
Hope this helps!