Take a multi-vitamin daily.
Drink or eat three servings of dairy or take calcium to support bones.
Use at least spf-15 daily, especially during the summer. Make up and moisturizers have spf in them, so no excuse.
Fruits and vegetables everyday.
Exercise 30 minutes a day.
Learn to take private time for yourself. Even if it means just taking a nice bubble bath once in awhile.
Laugh. It makes you live longer.
don't overwash your face.
don't wash your face with soap.
be gentle EXTREMELY gentle with your skin.
only use PH balanced cleansers so you don't strip away your acid mantle.
try to use oils for your moisturizers instead of the crap you buy at the store
or try a shielding lotion.
don't pick at your face.
good fats (omega 3 6 9)
eat more lean meats
what else ............................................... get your sleep
Mentally, everyone should try meditating. It really changes your life and what you attract into it. If you have depression please see someone to help you with it. I am trying to hit on things that people did not, most of the things on here have been what you shouldnt do (ie: Tan, smoke, eat fatty foods, etc..)..but by practicing being better to yourself will help in all these areas