Let a Boy or Girl Know You Like Them Without Telling Them

You want him to know, but you don't want to tell him?

Steps

Act like you enjoy the company of him/her. Be nice, laugh at jokes, do things for them, talk to them, and be confident!
Do not tell his/her friends if they're not your friends. They would probably tell the person you like them.
Find out if that person likes you without asking them. Ask his/her friends if they like you. They will tell that person and they will hint you like them..
Say "Do you want to do something together sometime?"
Make sure they hear you.
Make it obvious that you like them by listening and paying attention to them closely, but don't focus on every word they say or they might think you are creepy!
Don't nervously look away when you are having a conversation. Look him /her in the eyes when they are talking to you.
Make them do small stuff for you. If they do it pleasingly, then they might like you. Don't make them do so much stuff though, because they might think your just "using" them.
Don't tell them you like him/her on Facebook, Myspace, twitter, etc. because it will save you from going red in front of them when you see them later, and everyone else online will know too.
If you're talking to him, you should always feel like your talking to one of your friends, don't feel nervous and sooner or later he will catch on

Make sure you get to know the person you like before you do these tips!
Be confident! If you chicken out, it is okay, just make yourself want to try again!
Smile at them. If they are sad or in a fight, support them but don't make it obvious to let you get in trouble, if they need help and help them out if they really need the help.
Ask your friends if they think he might like you. Or say to them "Aw, your alright really! You know that, right?" if you are bantering together or something, that will give them a message.
Be yourself. Your crush likes people who are themselves.
Make hints, play with your hair in front of him.

Be yourself!
Do not act stupid around the person.
Never tell the person who you like straight up. Give it time.
If you never show that you're interested, then they might like you at first, but then find someone else.
Do not tell anyone who you like. If you do, rumors can spread!
Do not talk about other guys/girls around him/her.
Do not talk to the person 24/7. They will get annoyed.

Confidence
Person you like
Make sure you look good. You wouldn't want someone unhygienic (dusty, picks booger, bad breath, etc.) to come close to you right?