>generally eat healthy, sleep well and drink a lot of water.
>wash your face with cleanser, morning and night
>twice a week, use exfoliant
>after cleanser or cleanser+exfoliant, always use moisturizer
>if you're going out in the sun, use sunscreen. to make your life easier, you can get a moisturizer that has SPF and use that instead of the regular one if you're going out in the sun
>if you have problems with acne, try benzoyl peroxide
>wash your pillowcases often
>don't touch your face without washing your hands first
>certain foods may or may not trigger acne, such as peanuts and dairy products
all else fails, see a dermatologist.
also unrelated but you can get teeth whitening gel online and it actually works