The best way to make a girl notice you is to make the conversation about her rather than about you.
Ask her questions about herself, and look for things that you have in common. Don't fake interest; if the girl is intelligent, she will see right through you. Focus on things that she likes or does that you also have an interest in, and let her talk about these things. If it turns out you have nothing in common, consider it a learning experience; there probably isn't a future for you two.
Be Funny (But Not Too Funny)
Most people like to be entertained, and they will remember people who are entertaining.
The trick is to be amusing without turning into a buffoon. You want the girl to laugh at your wit and cleverness, not at how stupid you act. This requires self-control and calculation. Watch for the effect that your jokes are having on her and on anyone who is around you, and be careful to stop before you become tiresome. A single well-placed witticism will leave the impression of a clever and quiet person, but a barrage of slapstick comedy will make her think you're a clown.
Confidence is attractive to other people because it conveys the impression of a person who knows what he wants and believes that he deserves it.
Like humor, however, it needs to be kept under control. If you come across as arrogant or too full of yourself, your plans will backfire and the girl will probably want nothing to do with you. A good way to appear confident is to say a few things when you are asked questions but not talk too much otherwise. Quiet confidence leaves a good impression with girls.
Leave Her Wanting More
If you like a girl a lot, you might have the urge to follow her around, find out her schedule and "accidentally" bump into her a lot or prolong your encounters.
Resist this urge. The best way to get a girl to like you as much as you like her is to be friendly and confident and make it clear that you like her, but leave her more curious about you each time you meet. You should draw her in rather than pursue her, and you can do this by making yourself into a scarce commodity.