why do you want to? you have to be naturally attractive first, you can't just wake up one day and decide to be pretty, also a good personality goes a long way too, be sweet and talk to people and not just popular ones and only those who approach you, talking to lonely shy people, and especially a guy you like too (if you like guys)
Confidence is everything. If you believe you're pretty people will go along with it. But don't get conceited or else it will take away from your attractiveness. Try different styles for your hair. Try different styles of makeup that fit your face but don't overdo it. Make a change in your wardrobe that fits your style but also keeps up with the trends. Walk, talk, and act confident. Remember confidence is EVERYTHING.
Tip #1: Be pretty. Tip #2: That is not what you need to focus on. Tip 3#: Fuck what people think, being real is way more awesome, than being a little doll. Tip 4#: If you read this as; 'Tip hashtag1-2-3-4' you are doomed.