Just saw this on Dr. Oz today! Put some baking soda in a bowl. Then cut a lemon in half and squeeze half of the lemon into the baking soda. It will start to fizz. Don't mix. Dip a cotton ball into the fizz and apply to teeth. Then brush(no toothpaste) gentley. Haven't even had a chance to try this myself. Hoping it works!
Brush often, rinse with listerine, use whitening toothpaste, if you don't see much change, you can try the at home methods (crest white strips, tooth bleaching, etc.). If you still see no results and still really want results, talk to your dentist.