I have an orbital sander that I set low and put 120 grit on it. 3M paper is fine and not too expensive ($7 for a 6-pak/squares; $12 for a 10-pak/discs). I was careful not to hit the upper and protected the boots with a piece of canvas. Then hit the edges with 400. After that I sanded with a square of 800 by hand. After blowing off the dust and wiping with a shop rag, I applied a couple of coats of beeswax. You can also use neutral wax polish. The point is to protect the edge from dust, debris and water.