Natural ways to whiten teeth?

None really: Keep them clean by brushing and flossing properly and routinely after eating. Then see a dentist to discuss whitening methods that really work, if that is what you want.

Not too many: Some people do mixes of hydrogen peroxide with baking soda but it is detrimental to the enamel over time, best to get some whitestrips or see your dentist for a twenty minute in office bleaching.

Avoid the source...: I'm not aware of a good alternative to the whitening products readily available at your drug store or professionally through most dental offices. You may try to eliminate the source of the staining (speak with your dentist or hygienist about details), or use a whitening toothpaste. Good luck :).

Brush daily!: Routine hygiene can prevent the ugly tartar, plaque and stain build up. Try rubbing your teeth with your finger with. Little bit of table salt once a while!

Activated charcoal: Try brushing your teeth with activated charcoal for a few months and swishing with diluted regular 3% hydrogen peroxide.