A recent article in a psychology journal reviews the literature and explains why many standard "rules" are basically hooey. People who are lying don't fidget or avert their gaze more than others, for instance.
The authors go on to propose interviewing techniques for spotting lies. They say it's better to use an information-gathering approach than an accusatory approach. Among other things, they encourage asking temporal questions, using evidence strategically, and asking questions to increase the potential liar's cognitive load (i.e., make it harder for the liar to keep his or her story straight).
Aldert Vrij, Pär Anders Granhag & Stephen Porter, Pitfalls and Opportunities in Nonverbal and Verbal Lie Detection, Psychological Science in the Public Interest, vol. 11 no. 3, at 89-121.
Elizabeth F. Loftus has a brief editorial introducing this article: Catching Liars, Psychological Science in the Public Interest, vol. 11 no. 3, at 87-88. One interesting observation, of concern for social justice as well as spotting individual lies:
Using gaze aversion to decide that someone is lying can be dangerous for that someone’s health and happiness. And—what was news to me—some cultural or ethnic groups are more likely to show gaze aversion. For example, Blacks are particularly likely to show gaze aversion. So imagine now the problem that might arise when a White police officer interviews a Black suspect and interprets the gaze aversion as evidence of lying. This material needs to be put in the hands of interviewers to prevent this kind of cross-racial misinterpretation.It's interesting to me that, steeped in social psychology as she is, Loftus hadn't before focused on cultural differences like this.
(I'm currently reading The Warmth of Other Suns: The Epic Story of America's Great Migration, by Isabel Wilkerson, which piles layer upon layer of incidents when African Americans were slapped down–in small ways and large–for failing to look away and defer to anyone in power, so it's not at all surprising that Blacks would "show gaze aversion." I'm also reminded the passage in David Copperfield, which I just read, where the toadying Uriah Heep explained that his family had been taught "a deal of umbleness--not much else that I know of, from morning to night. We was to be umble to this person, and umble to that; and to pull of our caps here, and to make bows there; and alwasy to knowo our place, and abase ourselves before our betters. And we had such a lot of betters!" It's hard to like Heep, but this passage explained that his damage had causes beyond himself. Heep often was lying, of course, but you couldn't have told that by his "umbleness" alone.)