The outside of ginger is paper thin and using a vegetable peeler or a knife removes more precious ginger meat than is necessary. An ordinary kitchen teaspoon will work remarkably well.
Take a metal teaspoon and with a small amount of pressure, scrape the skin from one end to the other. Continue all the way around the piece of ginger until all of the skin is removed.
You now have a clean piece of ginger, ready to slice, dice or grate.