Fix body language - How can you tell by body language that a girl is into me?

How can you tell by body language that a girl is into me?

What are some body language indication?

If she shows it, look, touch, i don't know, it is an easy thing to tell
Great eye contact. Smiles when talking with you. Seems interested in everything about you. Touches you whenever possible, like on the arm when she is talking.
if you have to ask then no girl that you been around likes you, or you need to work on you observation skills
looks into your eyes.. touchy feelyy.. always looking at ur lipss..