Some signs that someone has a crush are held eye contact, hand gestures, such as increased touch, and use of humor. The way someone uses his voice and how he dresses are also indicators of a crush.
Someone who holds eye contact for a long time may have a crush. If a person is seen meeting a gaze and holding it, a crush is likely, as eye contact is a major sign of attraction.
How a person uses her hands is another indicator of a crush. Women have tendencies of flipping their hair or placing their hand closer to another person after something funny or meaningful is said when they have a crush.
Someone with a crush is also likely to use humor as a means of connecting with his crush. A person who makes a joke and waits for the other person to laugh at the punch line is likely trying to impress a crush. Someone who is enamored with another person will want to make her laugh.
A person with a crush may also match the quality of his voice to the person to whom he is attracted. It is not uncommon for people to show attraction by using a similar tone to the person they like. Another thing to notice about a person's voice is talking softly in way that shows that he is invested. It is also common for the person to use a playful and engaging tone of voice to show interest.
Finally, when someone has a crush, he takes more care with his appearance. A woman might put extra effort into her hair, makeup and clothes, while a man may make sure to be clean shaven if he knows that is what his interest likes.