Animals like to show off and make themselves look good when they are attracted to the opposite sex. It's called preening. You may preen by touching or gently twisting your hair around your fingers when you are with a guy you like. Guys preen as well.
When a guy likes you he may:
- Slick back his hair with his hand
- Smooth out his eyebrows.
- Straighten his shirt collar
- Smooth out the "invisible wrinkles in his pants
- Adjust his belt or pull up the waist of his pants
A man may also signal he like you by:
Turning his toes towards you when he is talking with you. (Notice especially if the toes stay pointed towards you when you are talking.) We naturally tend to point our toes towards people who interest us -- It's like a compass pointing towards true north.
The rest of his body may show he is into you as well. He could be talking to someone else, but if he notices you and he is attracted to you, he may angle his feet, his lower torso and/or his heart towards you and may not even realize it.
Notice his eyes to see if he is into you. When he looks you in the eye, his pupils (the black circles in the middle of his eyeballs) will get bigger if he likes you. If he likes what he sees he wants to see it well so the pupils dilate to take you in. Pupil dilation happens automatically when you are attracted to someone. Since a guy cannot control it, it is a great 'tell'. However it can also occur when someone is drunk or drugged or in low lighting so don't automatically whoop and say, "He loves me!" when a man's eyes dilate.