1- Be confident. Don't be afraid to be out there. Don't always be in the corner, because that doesn't get you anywhere at all. Stand out in the crowd. People like people like that.
2-Be yourself. I know some people don't really know how to do this. Express yourself through her clothing and personality.
3-Talk. Being in complete and awkward silence doesn't help you make friends. Don't be afraid to start some friendly conversation.
4-Don't be in the wrong crowd. Don't be with any smokers or drug dealers. That's gonna get you arrested, hurt or even killed. Don't drink alcohol either.