how to let a girl know that she's appreciated

Strike up a conversation. If you haven't met her yet, find something unique about her or the situation the two of you are in and say something about it. If she's a friendly person this should give you enough to talk about until you can start asking her questions to get to know her better.

Find something about her that is truly special. Does she have anything about her that is unique? A subtle little quirk or feature that you find endearing, but that no one else seems to notice?
Let her know that you think she's special without expecting anything (a phone number, a date) in return. If this girl is really interesting to you, there should be something far from the common that you notice. If she's good looking, she probably gets several compliments a day, so offer her one that is as unique as you believe she may be, like mentioning something about her personality - first impressions will make a huge difference. For example:
"Hi, I don't mean to make you feel weird or anything, but you've just got the prettiest freckles I've ever seen."

She'll probably smile, say thank you, look away, and maybe even blush. Remember that even if ultimately, it doesn't work out, you've at least made her day by giving her a true compliment.
Try to walk the line between a feel-good compliment and a cheesy pick up line. Be sincere about it, but don't go over the top.

Offer her your company, and walk away. That is, right before you leave, give her your phone number or screen name, or offer a time and a place to meet, and let her know that if she chooses not to take you up on your offer, you'll never bother her again. Don't give her a chance to accept or reject you. Make your offer and run. Give her a chance to think about it by herself, and wonder "Hmmm...I wonder what he's like." If you do this confidently and impressively, she'll feel compelled by her curiosity to get to know you better, and she won't feel like she's being pressured or chased. Also, the fact that she might never see you again will encourage her to follow up on any glimmer of hope she has about you being the guy of her dreams.

Don't look back. If she doesn't call or show up, leave her alone. She's not interested, and if that ends up being the case, don't take it personally. However, if she does call you or meet with you, you've probably swept her off her feet! The rest depends on chemistry and compatibility. Good luck!

Don't talk about a girl with another girl. Because she could like you & you would have wrecked your chances with her then.


Tips


- If she isn't interested move on, at least you tried.
if you love the girl, you won't give up easily, but if are unsure about your feelings, then try to be her friend and make her laugh and such and then try again at a later date.

Never Tell A Crowd of mates that you like that girl, its probley safer to tell your BEST Friend that wont say anything.

If you tell the wrong person and the girl dosent like you back you could face humilation for months as your friends well laugh at you.

Warnings



Be honest. No relationship can be based on lies. If a guy says, "I think you have really beautiful hair," and the girl is having an incredibly bad hair day, she's probably not going to believe him.
A girl is never impressed if she knows you're trying to impress her. Don't boast. Don't come off looking all proud and superior--that's the surest way to turn her off. Be yourself!

Some women will not be impressed with you if you slip them your number or screen name and run. This can come off as cowardly or insecure, which is very unappealing to some women. Confidence is the key.