The first and foremost step to lighten your complexion includes avoiding too much sun exposure.
Typically, the skin darkens when exposed to sunlight because it produces a substance, called melanin, to protect itself from the harmful solar radiation. Melanin is the pigment that gives color to our hair, eyes, and skin. And the more melanin your skin makes, the darker your skin becomes. Its also great to use sunscreen every time you go outside.
As far as lightening products, you can try creams and soaps that contain kojic acid, glutathione, aplha-arbutin, licorice extract, mulberry extract, and Vitamins C, E, and B3.
You can also try certain natural remedies such as lemons. Squeeze the juice from a lemon, dip a cotton ball into the juice, apply it on your face, then rinse off after 10-15 minutes.
Same way ,you may try potato. Peel the potato, cut it into small pieces, then apply the juice on areas you wish to lighten. For oily skin you may try the following natural remedies.
Egg Whites: High in vitamin A, egg whites can effectively dry out skin blemishes as well as tone and tighten up oily skin.
Lemon Juice: Lemon juice is a good source of citric acid that works like an astringent. It also has antiseptic properties that can lighten skin discolorations and restore the skin's pH balance.
Yogurt: Yogurt contains lactic acid that helps gently exfoliate the skin and absorbs excess oil from the face.
Tomatoes: Tomatoes are great for oily skin due to their cooling, clarifying and astringent properties. The high vitamin C content in tomatoes is very helpful for acne-prone skin. Plus, the natural oil-absorbing acids in tomatoes help get rid of excess oil.
Its best to consult your dermatologist to find out which of these options is best for your skin type.