Tanning is a common problem with Indian skin as we have less tendency to have a skin burn and our skin is rich in eumelanin. You can increase your intake of vitamin A (beta carotene), vitamin C and antioxidant rich food. These can be found in foods like papaya, mango, walnuts, tomatoes, lime, oranges, green tea. I would suggest you avoid sun exposure between 10 am and 4 pm. The right way to apply sunscreen is 1 tsp for face, one for each hand, 2.5 tsp for each arm 5 tsp for back. And you need to repeat it every 3 hours irrespective of the spf of the sunscreen. Also you need to focus more on boot star rating or PA index of sunscreen as the UVA
is responsible for tanning.