Answer: brush your teeth that's the best way
things you should not do: don't put lemons on your teeth if you think it whitens it does not it's bad for your teeth. The second is Carbon Coco don't use that black powder is known by a lot of people but a lot of the people who use Carbon Coco don't know that it is really bad for your teeth what it does is takes the top layer which is yellow and works like sandpaper removing the yellow/dirty part of your teeth the bad part about this it will make your teeth extremely sensitive.
hope this helps