Well I am not a guy, but I do like girls, so I might be able to be somewhat helpful.
The first thing that catches your eye is appearance. Before you can tell anything about a person, you see how they look, present themselves, etc. Guys (and girls) have different 'types'. Some guys like emo girls, some guys like red heads, some guys like girls with big breasts.
But that is only the first part. A girl might look nice but that doesn't mean you want to have anything to do with her.
Personality and compatibility mean a lot. This is what you want to put forward to the guys you are interested in. Be confident, guys think confidence is hot, and it is. If he sees that you are a strong young woman, he is going to be attracted to that. People will want to be around you. Don't be cocky, just know who you are, what you like and what you dont like.
Another thing is your ability to relate to the guy. If you like the same band, tv show, etc he might think that is really cool and in a way make you closer, as friends or even more.
Just remember to be yourself because guys have a way of seeing though you if you aren't. Because if you arent being yourself you wont have that confidence that is so attractive.
Good luck ladies. Happy boy hunting.