Most Helpful Girl
Look, if you pass a girl in the hallway and she looks at you, then it could be just because you are in her line of vision. However, if a particular girl always seems to catch your eye, then the likelyhood is she is interested in you. The clue is to see how her eyes look, when they look at you.
There is no doubt in my mind that eyes give a person away, because unlike other body language, you can't really hide what your eyes are saying, even if you try to.
If someone gives you an evil look, but smiles, you know the smile is not real...