First of quit smoking
and chewing tobacco habit if you have, don't take too much coffee or tea, brush after Every meal, at night brush with baking soda and rinse your mouth with lemon water
, apply lemon slice to your teeth, chew few leaves of basil leaves in the morning, regular intake of apple also maintain whitening
of teeth, use whitening toothpaste, visit your dentist
in every 6 months.