Through my early (and brief) curiosity about neuro-linguistic programming (NLP) techniques, I learned that when a person looks up and to their right, it's a good sign that they may be lying. Turns out, that probably isn't true. From the BBC:
The idea was tested by filming volunteers and recording their eye movements as they told the truth or lied.
A second group of volunteers was then asked to watch the films and try to detect the lies by watching the eye movements.
Co-author Dr Caroline Watt, from Edinburgh University, said: "A large percentage of the public believes that certain eye movements are a sign of lying, and this idea is even taught in organizational training courses.
"Our research provides no support for the idea and so suggests that it is time to abandon this approach to detecting deceit."
And if you really do want to be able to read people's facial expressions, you might start with legendary psychologist Paul Ekman's amazing books about the secrets revealed by microexpressions, such as "Telling Lies: Clues to Deceit in the Marketplace, Politics, and Marriage" and "Emotions Revealed."