@Clueless101,
Boys are as terrified, and clueless, and ignorant in this matters as girls.
The same could be said form a young man point of view:
Do girls really like boys who are cool, calm, and don't "nag" or do they really see that as an opportunity to walk all over someone?
The truth is that it depends alot of your own expectatives and of confidence.
So there is no specific thing that men want. There are multiple types of personalities in men, as well there are on women. So in this matter i do not agree with Jespah at all. We are not all the same, as women arenĀ“t either.
The best you can do is the next:
Be yourself: it sounds stupid, but what i mean is that if you like theather go to places where people who like theather have reunions. Having a hobbie in common is the best way to brake ice with boys. Do not be someone you do not like, if you do not like parties avoid them, you will loss your time.
Be kind: as i stated early, boys are as scared of girls as you are from them. A good attitude always attracts people.
Be confident: everyone at your age is insecure, there is no such thing as the overyly confident teen. It is not impossible as it sounds, be clear and direct, hide your fears, act like a secure person. Nothing is more attractive than a confident woman.
Your second question is far more complicated. It happens a lot and in both sides of the genders. It had happened to many bros, you are chasing for a GF no girl seems to care, but when you have one suddenly other girls notice. So i have no answer for this matter.