Anyways, back to the quiet girl. At first glance, she seems to be uninterested, almost snobby. She looks down when she meets eyes with you.  But I assure you, she does want to talk, but she doesn't know where to start. But what she lacks in social skills, she makes up in her intelligence.
She's a good listener, and is generally a deep thinker.
A quiet girl is attentive to her surroundings.
Her face will be blank, but inside, her mind is racing.