The basic idea, setting aside law enforcement interrogations and stuff where you're free to provoke responses and then evaluate them is to observe a subject for *clusters* of stereotypical indicators of deception.
Without the provocation part it's entirely passive and won't get you into trouble. Yes, it's not foolproof -- it's about as reliable as your own judgement. Your judgement, though, can get better through practice.
Women also don't have the magic ability to detect lies. As far as that goes, any lying, manipulation, rapport building, interviewing, etc etc is usually easier when dealing with the opposite sex and harder when dealing with the same sex.
Usually.