Empty your sink: Make sure there are no dishes, food or residue. Wash the whole thing down with some hot water & dish soap.
Get the worst of it: If you have super tough stains, mix together 3 parts cream of tartar and 1 part hydrogen peroxide. Rub lightly with a clean, non-abrasive cloth or sponge. Even the worst stains should come right off!
Rub it down: Get the inside of the sink wet and sprinkle some baking soda right onto the steel. You can add in a little bit of lemon juice or even use a 1/2 lemon as your scrubber for some extra power to your baking soda and to help deodorize (thanks Laura P.)!. Scrub it down, getting into every crevice and cranny, especially around the faucet. Use a toothbrush for tight areas and a non-abrasive sponge for the rest.
Get rid of water spots: Water spots on your stainless steel sink got you down? Don’t worry. Just rub them down with a little white distilled vinegar for a shine that won’t quit!