I wipe it out good when I'm done cooking.  Normally it will wipe out clean with a slick sheen left in it.  If something sticks I heat it up good and it'll burn some lose.  Then I take the Kosher salt and a paper towel and scrub it out with that.  Most times don't have to heat it, I just use the salt.  Also have cut a potato in half and that works the salt around instead of using a towel.  I never put it in water or use soap on it.  It's slicker than teflon.