Little tips and tricks that get one girl's attention might turn another girl's attention away, because every girl is different! So if there's a girl whose attention you want, what do you do? The following steps will help you get the attention of any girl whose attention is worth having, no matter how old, young, rich, poor, shy, or friendly she is.
Relax. When you are tense or nervous, you will be more prone to feeling embarrassed if you make some minor mistakes. Staying calm allows you to fully enjoy a girl's company. Be careful not to place all your hopes on a single girl; it will only make it more painful if things don't work out as you would like. Don't let any prior sour experiences prevent you from seeking opportunities that are available to you.
Respect all girls equally. You stand a much better chance of making a good overall impression if you treat girls that don't interest you just as nicely as those that do. This doesn't mean that you need to talk to or flirt with every girl, but don't ignore them or treat them dismissively. Don't talk to a girl about other girls' attractiveness; it's distasteful and can degrade the girl's opinion of herself. You generally shouldn't talk about past relationships you've had, or other girls that interest you; it detracts from building a new relationship.
Exhibit good manners. Girls love guys who are polite and courteous. Refrain from doing or saying things that many people consider offensive, including swearing and making sexist/racist/etc. jokes or comments. Saying things that you know would probably offend some people isn't a good way to make or keep friends. If you act like a gentleman, demonstrating your respect for females and other people in general, girls will be more likely to welcome your company.
Make brief eye contact. Don't stare, and don't avoid eye contact. When your eyes meet hers, hold that contact steadily for a second or two, maybe throw in a grin or a smile if it feels right, and look away and continue with your business. Something as simple as flirty eye contact can show a girl that you're both confident and interested.
Make people laugh. Girls love guys who have a good sense of humor, and the key to having a good sense of humor is to be lighthearted and unabashedly yourself.