Wear to school what you the most attractive. You do not need to overdo the makeup – you are at the age when you need much to embellish the face, and it still looks great.

Be always neat.
If you are not familiar with the object of your affection – get to know. To make it easier through mutual friends. If those are not available, try to strike up an acquaintance on the basis of common interests. Even if you don't like the music he listens to would not be a crime to do the time that you, too, crazy about her.
But do not expect that first encounter will lead to a serious relationship. His goal is to make you not other people, to open new ways for understanding each other.
When communicating with them, and all others in General, be confident. Remember that you are irresistible. As practice shows, the most interesting are the people who themselves believe in their attractiveness.
In those moments when you get the chance to chat with this guy, be in conversation, sincere interest in him and his Hobbies. Everyone likes to feel important to others, so give him the chance.
Smile. When had something to tell him, when you listen to him when he says something funny when he just casually catches your eye from afar.
Don't be too Intrusive. The guy needs to get used to it. Someone does it faster, someone longer, no need to rush things.
Try not to look too provocative and seductive. Yes, maybe the ultra-short skirts and ambiguous hints, is a very effective method, but if you need a guy who sees you as only a sexual object, but does not see the girl? Yes, and not very fit this behavior for a young lady. Be charming and cute.