Pupils dilate when they see something they find attractive. Also eye brows/eyelids/eyes can express a lot about how a person is feeling. If you understand what each one represents you can understand the person better.
Yes. Well I don't know what I look like when I look at the girl I like; but I will tell you how it feels. It feels like I'm staring into her. And the eye contact does not disburse. I'm not nervous. More or less, I'm extremely confident, and most of my thinking stops and I just do.
My friend C. just got married and a few years ago when she and her husband D. first got together after a few months I knew they would stay together and that he loved her more than anything cause of the way he looked at her. ^_^