Mansi,
You're still pretty young, so you don't have to go too overboard, but there are a lot of DIY things you can try.
Don't overcleanse your face for one, just get the oil off. Make sure you remove all your makeup before bed, and wash with a gentle soap, like glycerine.
If you have oily skin, you can use a clay mask once or twice a week to keep it clear. You didn't say what kind of condition your skin was in (dry/oily/combo) or if you have acne, but I gather it's pretty good - you're just going for prevention right now. Right? (Correct me if I'm wrong.)
In the morning, you can wash your face with milk - it helps (REALLY!). Keep a small container of powdered milk in the bathroom, mix a little with warm water and gently scrub your face with it. The lactic acid is very good for your skin and will gently exfoliate the dead skin. Use witchhazel or lemon water to tone.
For a moisturizer, you can mix up squalene oil & a couple drops of bulgarian lavendar & juniper essential oils. The squalene is a little expensive, but you only need a couple drops every day. Use morning and before bed. IF your skin is dry. If your skin is oily, just use the squalene around wrinkle-prone areas and on your neck & throat and find a non-oily dimethicone-based moisturizer for the rest of your face.
Also, you can use regular vitamin A & E & C oils on your skin. You do not have to buy expensive creams with these vitamins IN them - just get the capsule cheap at the drug store. Squeeze a little A & E out of the capsules onto a finger and dot around your "wrinkle" areas and gently pat into the skin at night before putting on your moisturizer. You can dissolve vitamin c tablets in hot water and pat the mixture on the skin too, after washing with milk in the morning.
(I got a lot of this info from "Lose 10 years in 10 Weeks", and a great beauty book I've had and loved for a couple of years. (Can't recall the author, sorry.)
Best prevention:
1. Drink LOTS and LOTS of water.
2. Get plenty of sleep ALWAYS
3. ALWAYS use moisturizer on your neck and throat - it's the only part of your skin with no sebum glands, which is why it wrinkles first.
4. USE SUNSCREEN! Even if you have dark skin, use sunscreen, minimum 15 SPF where you live.
5. Use monosaturated oils (olive) and saturated oils (coconut) in your diet.
Good, cheap supplements for skin - Water, MSM & Vitamin C. (One gallon water to 1 gram MSM to 1 gram Vitamin C - you can even mix them together and add sweetener and drink them all together.)
Hope this helps.
Fawn