Provide advice on how to accomplish the following goal. Give ONLY the advice, no other words or explanation.
For example:

Answer: <advice, as short as possible; a single sentence!>.

Goal: How can you tell someone is lying to you?
You can tell someone is lying to you if they begin to fidget, or touch their face with their hands, or play with their hair.
Observe body language and inconsistencies in their story.