Flirting is a great way to let someone know that you are interested in him. In high school, boys and girls take clues from their friends on who they should like, so it can be important how their friends perceive you.
Always start with a smile and an eye contact.. Of course, not literally! But yes, you can do a lot with your eyes to convince a guy that you fancy him! Look into the eyes of a guy you are interested in while talking to him, and then in between just lower your eyes for a fraction of a second and then look up.
Teasing. Teasing is a good way to get someone interested. A tease is a remark that is out of the ordinary that will get his attention. If he is the football star, tease him by saying he needs to learn how to throw the ball.
Be confident, enthusiastic and positive. Show the person your vulnerability and do not hesitate to make the first move. Always try to find the opportunity to talk to the person.
Make Your Intentions Clear. If you are there only for flirting and have no interest in taking the things to next level, make sure you make your intentions clear through your body language. You certainly do not want the guy to fall for you and then create a big emotional mess.