-use whitening strips:
if you're going to use some, then make sure they get approved by the ADA (American Dental Association) or any dental association because they can contain some chemicals that can damage your enamel. these can really help make your teeth white due to the gel on the strips.
-thoroughly brush & floss:
definitely make sure you floss after brushing, it can help remove any stuff that prevents your teeth from whitening. it will remove plaque in between your teeth so those spots can be whitened as well.
-use whitening gel:
use an ADA-approved gel to make your teeth more whitened; it's as simple as brushing the gel onto your teeth with a small brush and leaving it on for at least 2 minutes, then spitting out the remaining gel and rinsing it all out with water.
- use whitening toothpaste:
here are also whitening toothpaste you can use, it must be ADA-approved and you can use it in the morning and after supper like you would do with your normal toothpaste.
-use hydrogen peroxide:
you can do this at your house at any time, it is already approved by the ADA so you don't have to get it approved! you can mix it with water as a DIY mouthwash! or mix it with baking soda to use a teeth whitener.