Summarize this article:

Stainless steel scratches easily, and even a mild kitchen scrubbing pad will mar the surface.  Use a microfiber cloth. They work better than lint-free cotton because they leave less fibrous material on the surface of the stainless steel Clean and shine your refrigerator with paper towels. If you want a super, non- streak shine, first clean the surface with the microfiber cloth and your favorite cleaning agent, and then wipe down the refrigerator with paper towels.

Summary:
Choose a nonabrasive cleaning cloth.