Instructions

1

The first step to know if someone is lying is to watch if they scratch and touch their face. When children are caught telling something that is untrue they will cover their mouth as a natural reaction. This is an extension of that in adults, they will touch their face as an uncomfortable sign that they are being dishonest.
2

The second step is to look if they have their legs crossed when they are telling you the story in question. This is the bodies way of trying to cover itself and is the a sign that the person is trying to shield themselves from you. It is a sure fire sign that someone is uncomfortable with what they are telling you and a sign of someone who is lying.
3

The third step is to look if someone is biting their lip as this is a sign of lying. Just like covering your mouth this is a childhood reaction to lying, this is one of the biggest giveaways and a red flag that what your hearing is not the truth.