Put a tiny bit of toothpaste into a small cup, mix in one teaspoon baking soda plus one teaspoon of hydrogen peroxide, and half a teaspoon water. Thoroughly mix then brush your teeth for two minutes. Remember to do it once a week until you have reached the results you want. Once your teeth are good and white, limit yourself to using the whitening treatment once every month or two.
Dip a cotton ball into the lemon juice and baking soda solution and apply it to your teeth. Let the lemon and baking soda solution sit on your teeth for around a minute. Brush your teeth to remove the acid. I saw results the first time I tried this.