The action of lying is a complicated thing.
“Did you know how this happen to him?”
“No”
The first part is always the easiest, a simple ‘no’ or ‘yes’. But then the tricky part is convincing the fool you’re speaking truth.
“Are you sure?”
“Yea, I don’t know how he broke his leg.”
You have to balance a calm demeanor with some undertones of emotions. The easiest way to do that is turn the accusation on the accuser.
“What? You don’t believe me?”
“Of course I do.”
The quintessential part is your face and eyes. To convey a certain emotion like surprise or confusion it is very important that you don’t overdo it.
“Then why are you doubting me?”
“I’m not I’m just trying to find the out what happened to your brother.”
You over-dramatize an emotion and it’s clear you’re lying or hiding something. A half-second or so should do the trick. It’s the same with tone, small hints of anger or sadness in your voice is perfect.
“I already told you the truth, mom”
“I just thought you would know. You guys went to the park together didn’t you?”
It’s also easier to lie if you mix in the truth with your deception. You’re not technically lying if you add in some truth. There is deference between the truth and honesty.
“Yea but he ran off with his friends after a while. He was gone for twenty minutes before I found him.”
Also it is very important that you don’t adopt an emotionless mask while you’re lying. To little emotion is as suspicious as too much.
“Well thank you for being honesty with me”
“No problem”
If you’re lucky you won’t hear your subconscious chanting, “Liar, LIAR, LIAR!!!”