It can be frustrating when you're interested in a girl who already has a boyfriend. You might think about her, but there's not much you can do because she's with the other guy. However, there are some steps you can take to try to win the girl you want even though she's dating someone else.
Do nice things for the girl. Help carry her books if she needs it. Help with her locker if you notice she needs an extra hand. Being nice to the girl will lay the foundation for better things to come.
Become friends with the girl. Be her shoulder to cry on when she has troubles with the current boyfriend. Tell her she deserves better when she is ready to hear that. Be careful not to let on that you're interested just yet.
Watch what you say to the girl and your friends. You don't want it getting back to her or her boyfriend that you are interested in dating her. Don't profess your undying love. Save that for when you win her over. Keep things cool and friendly.
Wait for her to decide on her own that she no longer wants to be with her boyfriend. Relationships tend to work out best when they are not forced and come naturally. Watch for the signs that the old relationship has ended.
Ask her if she'd like to get ice cream or a soda together as a date once she is free and clear of the old boyfriend. This is when you can lay on the charm and talk about the two of you being together as a couple.