I use those mini alcohol wipe swabs that the healthcare people use to clean your skin before giving you a shot. The ones that are individually wrapped come in a box of 200 for about $3.00 at any drug store. I had been annoyed at how greasy the case can become and these do a good job. Soap and water works, but this is quick and easy, and dries instantly. Obviously you get the added benefit of disinfecting your case too, just don't use them on you screen because the alcohol will strip off the oleophobic coating. My lint-free cloth is then only used on the screen which keeps it cleaner longer.