There's all kinds of advice out there about how to get girls to like you more, but keep in mind that doing anything that feels awkward or uncomfortable will probably not work for you. This includes pretending to be someone you're not. If you somehow manage to fake your way into a relationship, chances are it won't last long.
However, there are a few things you can do to increase your odds of getting a girl to notice you, and to say yes when you ask her out.
Clean up. As a teenager, you need to be extra cautious about staying clean and odor-free. Shower daily, use deodorant, and brush and floss your teeth twice a day. Before you try to get close to a girl, make sure you smell good. You can use cologne or aftershave, but do not use too much. Ask a female friend or family member for advice if you want to know which scents smell OK on you.
Pay attention to your hair and clothes. Don't dress or do your hair in ways that are totally out of character for you, but keep in mind that teenage girls, and females in general, will notice your outer appearance before anything else and they may not take the time to get to know you further if you look sloppy or if your clothing is outdated.
Try to hang out with the girls you like and their friends in casual settings. This allows you to get to know a girl better and see what her interests are, and let her get to know you in a non-threatening way.
Maintain a strong sense of who you are, as you pursue girls you like. Do not change to become what you think they want, and do not put them on a pedestal and immediately shower them with compliments, begging for a date. Girls like guys who appear confident, intelligent and who won't fall apart if they get turned down.
Show your interest in dating a girl when you suspect she may be interested in dating you, too. Do not wait too long, as becoming close friends with a girl may make her less likely to see you as a potential boyfriend. Sometimes, once you have been in the "friend" category for too long, it's hard to go anywhere else.
Keep it light and casual when you start dating a girl. Coming on too strong with gifts, poems and passionate declarations of love can overwhelm her and scare her away. Let your relationship develop gradually, finding common interests and spending more time together, while keeping your own friends and maintaining your own life.