Robert Heinlein said there are three ways to tell lies. First, look the other person dead in the eye and lie through your teeth. This is the method of beginners. Second, mix the lies with a fair dose of truth so that it's hard to tell one from the other. This is the method of politicians. Third, tell the truth, the whole truth, and nothing but the truth -- but tell it so unconvincingly that nobody will believe you: this is the method of the masters.
But a couple of things wannabe liars would do well to remember: Never tell lies with numbers in them. Never tell lies to anybody who is more intelligent than you. Never tell lies to anybody who has a better memory than you. And never tell lies to your mother. Mothers have an infallible built-in lie detector.
Little idiosyncrasies and ticks for each person vary but are dead giveaways if the liar is not experienced. Rubbing their eye, clearing their throat, touching their face or hair are common indications when a person is lying. Shuffling on the spot, sweating, stuttering, facial twitches, fidgeting, touching jewelry, facial expressions that are not suitable for the situation (like a smile or smirk), basically anything that seems out the ordinary for that person when they speak to you regularly. People often avoid eye contact or glance around rapidly, and if the suspected liar is looking upwards and to the right it means they are accessing their imagination- but be careful! Sometimes looking upwards to the left (memory) and upwards to the right (lie/ imagination) may be reversed with individuals. Try testing and taking note of the suspected liar to be sure.
I learned this on a TV show called Brain Games. Assuming that the person is not an expert, do this trick next time you meet him: tell him you're going to ask him a question, but his answer must be "no." Ask him is he's wearing a shirt. His answer will be no. Now, while he's answering or immediately after, look for something that uncharacteristic. Did he twitch? Did he shuffle around? Did he blink several times? Did he look back and forth? Did he run his hand through his hair? Did he crack his fingers or twiddle his thumbs? Did he tap his foot? Did he shake his leg or arm? Did his voice crack? Did he stutter? If he did anything unusual, he will most likely do that when he's lying. It works better on people if they don't know you very well.
Psalms 26:4 says "I have not sat with men of untruth; and with those who hide what they are I do not come in."So it is very important to have true friends and companions that do not cause a reasonable suspicion that they are lying to you constantly. Maybe you can think why you believe you are being lied to in the first place. Maybe there are some underlying issues you need to discuss with this person.