alot of the over the counter type stuff doesn't really do much.
I do brush with a whitening toothpaste, but i then follow up with brushing my teeth with pure baking soda. It leaves my teeth super smooth and just as clean as if i have just left the dentist after a professional cleaning. I prefer powdered toothpaste for the same reason. Tea, coffee and dark sodas and even colored drinks(my favorite, Ribena) will stain teeth, so brush after you drink whenever possible. i have a toothbrush and a small tube of paste at work in my desk, and in my purse. A professional whitening is usually the best as far as results go, but if you have any discoloration from any previous medical problems then they are usually there to stay. If stains are from food and drink over the years then just steady brushing 2-3 times a day should help over time. Some of those whitening strips help some too so you might want to try those along with increased brushing(be careful not to make your gums sore) best is to use a "soft" tooth brush as this allows the brissles to also slide under the gums cleaning away debris helping prevent gum disease. By the way if you smoke that can also discolor teeth and cause gum recession. Dont forget to floss.
Mikala