I saw this in a magazine a while ago, and it changed my life. So obvious, so useful, so easy. If you fold your sandpaper this way, there are are no sand-on-sand sections wearing each other out. Each sand side is protected by paper. It's beautiful.
The picture says it all:
- Take a square of sandpaper
- Make a tear halfway down the middle
- Fold one "ear" down
- Fold paper side over the ear and fold down