Any way to make my teeth naturally white, or only through bleaching?

Consult your dentist. Bleahing of teeth removes only external stains.If your enamel is naturally yellowish, there is a limit to which your teeth can whiten after bleaching.It also depends upon your expectations.If you see movie satrs with really white teeth,chance are that they had procelain veneers.Porcelian veneers can give you color you want & also can give you perfect anatomy & alignment.Consult dentist for options.
Whiten teeth. You can try tooth pulling, rinse your mouth with coconut oil . Many of my patients have had good results, not as good as professional whitening at a dentist though. .
Depend. You can keep your teeth clean by meticulous brushing and flossing to prevent staining from food. If you want to have really white teeth you need to use bleaching.