If you want to know how to make a guy fall in love with you, then this is not the article for you. This is for those who have noticed a guy and want him to notice her back (getting him to like you is a whole other story). Luckily, getting a guy to notice you is easier because it involves the use of basic social skills. You should be honest, direct, pleasant, and reasonable.

[edit] Steps

Be sure that his attention is what you want Don't try to get a guy to look your way you want attention and you want to feel good about yourself. You don't want to lead someone on like a puppy taken out for a walk. You could end up in a very awkward or uncomfortable situation--see the Warnings below.
Be yourself. Everyone probably says this, but it's true! No guy wants a girl to pretend she is something she's not. As a general rule, guys don't expect girls to change. Resist the temptation to put on a show or to do anything that just isn't you just to get his attention.
Get a new look. Don't change who you are (you never want to do that because you'll actually end up changing yourself) just try something different; if he doesn't like you for who you are let him be. Try a new hairstyle, new clothes, etc. It's a good idea to change things up once in a while, just because variety's the spice of life, and it might help you catch his eye. Try being that tough girl who is different from all the other okay looking girls giving him the eyes, because beauty is common, but a good outlook and a great energy are very rare.
Smile and make eye contact. Whether closed-mouth or open-mouth, do it. Unless it really makes you feel artificial, learn how to shoot people a reassuring smile, letting them know that you're a happy and confident person who wants to enjoy life. The idea is to communicate that you're inviting their company.
Flirt. Do it as little or as much as you want, but remember that too much flirting (especially with other guys) will likely get him to take notice, but perhaps not in a good way. If he reacts and you don't think its real (he's just doing it because you're there and you're a girl and he thinks he can do better, let him know he can't). If he is faking it, call his bluff and say something that makes him know you don't think he is 'all that'. For example, if he comes close, pull a face and offer him gum. This will unbalance his ego.
Hang out with him often; you don't always want to be hanging around because you might look like a bug always around and never going away. Start slowly like a movie or party try not to make it so noticeable cause he might not be interested.
*Whisper Whisper*

Talk to him. Try to get to know him a little by discussing things you have in common. A good way to start a conversation is to ask him a question. Listen to him and don't interrupt him when he is talking. You could even compliment him or ask for help. A good opener is spray two different perfumes on each wrist, then go up to him and ask him his favorite. This should get him to talk to you. Also be friendly to his friends to help him feel more comfortable around you. Some guys don't notice girls unless they talk to the guy.
Be assertive. You are the girl. You have the power. A lot of guys are shy and awkward around girls they like, so don't hold back. Do what you want to do. Boys like a powerful girl. Be decisive. Tell him what you want him to do, etc.--just don't get too bossy!
Make him feel special. There's got to be a reason that you want him to notice you, and that's because you noticed him first. Let him know--subtly--that you're interested in who he is, and that you sincerely want to get to know him better.
Be brave. Stand up for who you are, and what you believe in. Ultimately, this will catch the attention and respect of someone who is going to work well for you, even if it turns out not to be this guy.
Don't be a slob! It's a real turn-off for a guy when he notices a girl hasn't brushed her hair or wears the same outfit every other day. Clothes, makeup, and jewelry are the typical items many guys expect girls to wear. Even if you don't fall within the typical expectations, just looking presentable is always desirable--irrespective of who is the guy or girl.
Just Talk To Him. When it comes down to it, talking to a guy, and flirting with him will get his attention, and if it doesn't nothing will.

[edit] Tips

Be sure to invite him to every party you have. Do not give him the first invite, and don't seem so hyper and excited that would make him rather want to shoot himself than to come.
Be sure to have gum, breath mints, Listerine strips, etc. around in case you need to freshen up quickly, especially if you're hoping to start a conversation.
If you have gum or mints or whatever in your purse, try offering him a piece but give a best friend a piece too, so it's not that obvious.
It's always a good idea to keep yourself well-groomed. While there are guys who get uncomfortable and intimidated if you're all dolled up, it never hurts to stick to a few hygiene basics: shower, brush your teeth regularly, use deodorant, keep your hair decent (not perfect, but decent), and take care of your skin. Better yet, stay healthy! Exercise and a mixture of good and bad food is better than going on a no food diet. Exercise releases a chemical that makes you feel good about yourself. If you feel good about yourself you are very good at flirting. Chocolate releases another chemical the makes you feel very happy, if you don't eat too much that is.
Speak your mind. You're not a drone, and any guy worth having will love it. Just don't scare them by going into a spiel. It's a turn-on to see a girl who loves her mind, not one who's bent on world domination. Likewise, don't get caught up in complaining (about yourself, others, your circumstances). Negativity pushes others away, and it lowers your self-esteem.
If you cannot relate to any of his interests, or even make a genuine effort to get into it, there will never be ground for a lasting relationship anyway. Dump your intentions now.
Being too straightforward might mean leaving him bored. One way to get someone's attention is to make him curious, and that means leaving him guessing to some degree.
React to his jokes. If they aren't funny, say so (otherwise he'll keep telling the same bad jokes). Then tell a couple to make him laugh.
When you are at a party, hang around with some friends (and him) and you will all have a good time.
Hang out with him and his friends a lot.
Go to the movies with him, and put a bit of perfume behind your ears so that he can smell it and want to come closer to you. Scary movies are better because you can curl up closer to him more than other times and hold him when you get scared. Plan everything you do BEFORE you do it. Dates where you go to a movie and sit through it with nothing happening between you and then you both go home, suck. He's going to enjoy that so much! NOT.
Put lip BALM on your lips. This way he will notice that they are slightly shinier and if you get close he will be able to kiss them. Guys really don't like gloss, they find it sticky and it truly doesn't taste good. Fruit flavored balm is best. Or, if you must wear lip gloss, a good kind is NYC Kiss Gloss. It is flavored with no sticky feeling.
Be mysterious; keep him guessing. Don't overdo this; it will make him frustrated (not to mention confused) if you do it too much.
You have to be able to know how to not be so serious! Be laid back, be fun!
Never ask him out through a friend! He`ll be weirded out and he might just say no. In fact he may never speak to you again and will be moody for the rest of the day.
Remember that the boys are usually the ones who pursue in a relationship. Let him ask you out. This builds up his confidence and he will treasure you more if he knows it takes work to get to you.
Be outgoing and make small talk every once in awhile. Just remember not to be nosy, though.
Don`t ask him how you look! It will just make him uncomfortable and he`ll think you're too self-absorbed for him.
Make sure you don't say anything that you think might offend him.
Find out what his favorite color is -- subtly, don't just go up and ask him unless you're really confident. Then slowly integrate it into your wardrobe. Don't go out and buy piles of it, but if he really likes that color he'll notice the clothes and therefore the person in them. Don't buy the clothes if you don't like the color. Don't buy expensive things just to get noticed. You're still your own person. Guys do not like it if you're fake!
These will get a guy to notice you (approved BY a guy): When you have come familiar perhaps you could touch his arm or as I've found very handy just when you are walking hold your hand slightly away from your body so he can hold it. Also you can lean toward him when your sitting next to him, but not too close. You could also use his shoulder as an armrest (but whatever you do don't lean on it) or place your hand upon his shoulder very gently.

[edit] Warnings

Be careful whose attention you're getting, and what kind of attention you're earning. Being noticed by a sleazy guy who'll pressure you to do things you don't want to do or a needy guy who'll cling to you and make you feel limited is something you can avoid by being wary.
You can't get everyone to notice you. Remember that guys come and go, so do not stress yourself if things do not work out in your favor.
Being too obsessive can do the opposite of what you want to achieve, pushing him farther away. If he just won't become attracted to you, leave it alone. Do not push it, or things might get ugly, and you'll earn a bad reputation.
Don't show off too much flesh, especially if he would always look! Keep him under suspense, in case he thinks you're a push over.
Realize that sometimes things might always be better as friends, but if he wants to just be friends take the opportunity, because thats better then nothing, who knows he might end up liking you after a while.
If you want him to be attracted to you, make sure he's single first! You never want to be with a man who is taken. you know what they say, what goes around comes around.
DON'T BE TOO DESPERATE!! Guys hate it when girls try really, really hard to impress them, it just gets out of hand and it's a real turn off for them.
If he doesn't seem to be getting all the hints after a week or two... he probably won't...ever. It sucks, but you have to give up. Pushing yourself at him will not help... AT ALL.