You will need: a shallow bowl, baking soda, aluminum foil, warm water & a soft brush.
Place the foil in the bottom of the bowl and then add your jewelry. Cover with baking soda, and fold the foil over the jewelry making a little pillow...don't close it off completely because water won't be able to mix with the soda. Pour warm water over the entire pillow and let set for a couple hours. After that time, remove everything and rinse off the jewelry while gently brushing away any dirt. You might have to do process over again depending on how tarnished it is.