I was sick of sandpaper littered around my work areas, losing sandpaper, going to the store and buying more when i knew i had some somewhere in my house!
So I started storing my sandpaper in an old expanding file folder!
I store the sandpaper by grit size and by sandpaper type. I separate the wet sandpaper from the woodworking paper and all the different grit types.
Now when i need sandpaper, I open up the folder, find the grit and type I need, no hunting for paper, no questions whether or not i am out of a particular grit!
You can pick up an expandable file folder at Amazon here: Expanding File Folder