Be confident! Nobody will want to be you if all you do is stare at the floor! Keep your chin up and make eye contact with everyone. Smile at them, too. That shows you're confident and that you know what you're doing - even if you don't. They will admire your confidence (but don't become overconfident).
Be stylish. It's very important. People will judge you for what you're wearing. If you can purchase designer clothes, why not? But if you can't, shop in Forever 21, Charlotte Russe, American Eagle, Urban Outfitters, Abercombie and Fitch etc. instead.
Be hygienic! Nobody will want to be around you if you smell bad: they'll avoid you! Bathe or shower every day, and wash your hair every other day. Wear slight, natural makeup: lip gloss, face cream and maybe a little eyeliner. Brush stylish your teeth and floss, and take care of your skin by drinking at least 8 glasses of water daily. Wash your face every day, too. It must be flawless! Brush your hair twice a day.
Be organised: Keep your things neat: don't lose them. Make sure your room is clean, and just everything you have. Keep them organised!
Have an amazing room: No matter how small it is you can make it look bigger and cooler. Clean your room manually so it doesn't get dirty. Get lamps, they light up the room and make it look bigger. Don't cover all your walls with pictures and posters, that will make them look small. Just a few would do the trick.
Create your own clique.
There must be 2-4 girls in that clique. That doesn't mean to judge people by their looks, but your friends have to be pretty, or else it won't work. But, don't dump your old friends for that! You'll have to have the stylish girl, the smart girl, the sporty girl and the party girl! You will be the flawless foursome.
Get your clique out there.
Host a party at one of your houses, and invite as many people as you can. That way people will get to know you and they will think you're cool, but make sure your guests don't get bored! That would be very bad for your reputation.
Talk to boys.
Believe it or not, boys talk more than a lot of girls. If you flirt with one boy, all of his friends will know who you are on the next day. Be friendly around them and don't just call every boy a jerk.
You and your friends have got to be super duper close, so host a sleepover every Friday night. Try it like this: first Friday at your house, the other in your other friend's house and so on. Share the gossip, but don't start rumors.
Keep a diary.
It will be fun. Being popular means lots of drama, so you are going to have to need something to pour your feelings in. Just make sure that it's in a safe place for nobody to read!
Be mean when necessary.
Don't let anybody bring you down! If somebody is being mean to your friends, be with them on that one, and they will be there for you too. You must have the best comebacks or else this one won't work.
Don't be mean to everyone! People will hate you and you will be famous for your bad attitude and that isn't what you want.
Have a cell phone.
That's a must, you have to keep in touch with the people around you. Get everybody's phone number and keep them just in case.
Join Facebook/G+/Skype/ooVoo, just anything that has a chat system.
Add everybody you know, just not the lame people... or they will annoy you and brag about talking to you... and there goes your reputation. But don't be mean to them!
Don't change who you really are, because in the end it's still you. Be yourself, and never lose your personal flair!