Hi Girly :)
First things first -- before we start, I just want to make one thing clear. Being 'girly' doesn't mean you need to be obsessed with pink, squeal at everything that freaks you out or act like a total airhead. Being girly is simply embracing your femininity and paying a little attention to how you look. After all, the way you carry yourself can really say something about who you are.
The first thing to do is update your wardrobe. What are the stylish girls around you wearing? You don't need to buy designer clothes and spend a ton of money. If you're uncertain about what you should buy, start with the basics.
Get a pair of fitted jeans -- make sure they're not baggy around your thighs and knees but make sure they're not too tight that you have a muffin top! Get one that is boot cut or straight leg -- flared bottoms aren't as stylish and can make your outfit appear messy. If you want to be really stylish, get a pair of skinny jeans.
Look for versatile tops if you're not planning to go on a shopping spree. A couple of fitted tank tops/beaters, long sleeves and some dressier tops will do the trick but if you're uncertain of what to choose, keep it simple. You always have the option of dressing up your outfit by adding a statement necklace, a pair of fun earrings and some bangles.
What about your feet? Get a pair of ballet flats. They're not as 'boyish' as runners and not as impractical as wearing stilettos everyday. Depending on your age, you should also invest in a pair of heels for times when you need to kick your outfit up a notch.
For an easy outfit, slip on your jeans, ballet flats, a tank top and top it with a long cardigan. Put on some accessories. If you're wearing big earrings, go small on the necklace or don't wear one at all. If you're wearing a chunkier necklace, go simple with the earrings.
(You can get a free style report of the top 10 things every girl should own howtobegirly.com)
Lastly, in order to make your outfit look hot, you'll need to look hot too. Ever see a not-so-well-put-together girl wearing designer clothes? Hmm.... not so hot. Really, its not about the type of clothes you wear, its HOW you wear it. So apply a little mascara, bronzer and lip gloss -- if you don't usually wear makeup, this is a good starting point. You can also line the top of your eyelashes for more definition or line your top and bottom lashes for even more drama. And your hair? Make sure it looks well groomed. Is it frizzy and messy? Does it need to be straightened? Is it flat? Flat hair is one thing: boring. Tease your hair a bit for some volume.
Changing your appearance is can definitely make you look more feminine. When it comes down to it, you probably don't really need to change the way you act (unless you're rude and completely ill-mannered... which you're not right?). You can feel feminine without having to do a whole lot of 'girly things.' I'm definitely a girly girl, but I also enjoy being one of the boys.
Don't fret sweetheart, you're almost there.
On teasing hair: http://www.hairboutique.com/tips/tip100066.htm
On Being Girly: http://www.HowToBeGirly.com