He constantly smiles around you.
If a guy frequently smiles around you, you may be the reason he's smiling. It's even better if he looks you in the eyes when he smiles. If you notice that his mood brightens up when you walk in the room, that's a good indicator of his feelings.
He compliments you frequently.
If a guy is quick to compliment you, he's definitely noticing your positive traits. This is even more telling if he compliments you on unique and special things, such as your talent or your heart; such comments are heartfelt.
He asks you questions about yourself.
If a guy asks you several questions about yourself, he wants to get to know you better. He also may be trying to probe your interest in him.
He tries to get you alone.
If a guy tries to get you alone, he wants to spend time getting to know you and you alone. He likely does not want any distractions around, or he might even want to reveal his feelings for you.
He brags a bit.
If a guy brags a little around you, he's trying to show you that he's desirable. He may talk about what sports he's skilled at or awards he's won. Build him up if you want him to feel your appreciation, and maybe even make a move.
He tries to make you laugh.
A guy who tries to make a girl laugh cares about her reactions to him. He wants to see if he has the ability to satisfy her and make her happy. Laugh at his jokes and give him a confidence boost.
He stands up for you.
Standing up for a girl may be difficult or uncool, but if a guy defends you, he's disregarding other people's opinions and acting on his feelings for you. This is a particularly telling sign, since it shows that he's willing to sacrifice his reputation for you.
He looks you in the eyes for prolonged periods of time.
If a guy constantly tries to catch your eye, he wants to connect with you and try to determine how you feel about him. A guy will look you in the eyes for a long period of time if he's interested.
He touches you while talking to you.
A guy who touches you -- on your arm, hair or cheek, for example -- while talking to you is subconsciously expressing how he feels. A guy will attempt to be physically close to you if he likes you.
He makes a fool of himself in front of you.
A guy who is into you will make a total fool of himself in front of you. He may do this by showing off or acting silly. You may think he's crazy, but he's actually just feeling high on adrenaline and his feelings for you.