The body language project dating attraction and sexual body language
One theory estimated that around 90% of the "meaning" derived through human interaction is made through non verbal communication.That theory is however now widely regarded as flawed, with most researchers and experts now broadly agreeing on a figure of around 50-60% of all human interaction and communication as being non verbal.Also slight parting of the lips while looking at you is recognised often unconsciously as an indicator of sexual interest.Many women unconsciously twirl or flick their hair when in the company of a man they're interested in. Body language around the world - aka kinesics - relates to non verbal communication through body language gestures, facial expressions and posture, and can be done consciously or unconsciously though more often unconsciously.
The "open stance" where he is standing up straight with shoulders back and head up (but not with arms crossed) indicates that he is either showing that he's open and available or that he's a strong and dominant male, or of course both.
There are too many explanations for this to go into here, one being that it means she unconsciously exposes her inner wrist and forearm - an erogenous zone - suffice to say that it is well accepted and established as an unconscious - or conscious - flirting gesture.
Pointing her knees towards you that a woman is feeling relaxed and at ease with you.
The mouth and lips Slight licking/moistening of the lips is a significant signal, much more so if she does it while making eye contact.
Many psychologists are of the opinion that the popularity of red lipstick is unconsciously due to its potency as a subtly suggestive image of labial arousal.