•No eye contact. A lot of information is conveyed through eye contact, and most people have an extremely hard time lying to someone while looking directly into his eyes. Sometimes this will only occur at the moment of the lie, a brief glance at the floor or to the right. Again, some will try to sell the lie by making and maintaining eye contact fiercely, much more so than usual.

•Stress gestures (rapid blinking, scratching, itching, swallowing, fidgeting, etc.). If discovered, a deception carries much greater risk of punishment than simply telling the truth, and people understand this. This uncomfortable situation will make them uncomfortable, and they will act accordingly.

•Looking up to the right. Looking up and to the right stimulates the part of the brain associated with imagination (that is, making things up), whereas looking up and to the left stimulates the part of the brain associated with recalling memories (that is, telling the truth).

•Touching the nose and covering the face/mouth. Habits from childhood, these gestures are a subconscious attempt to “cover up” the lie, and put distance between the liar and you.

•Rise in vocal pitch. Another product of stress, the liar's voice will get higher and squeaky. This should be noticeable if you are familiar with his normal speaking voice.
•Wide-eyed, innocent look. Another product of childhood fibs, based on the “who, me?” fake innocence usually associated with a kid denying he has his hand in the cookie jar while it is still in there.

•A noticeable pause in speaking. Most people lack the ability to come up with a plausible fiction in an instant, so they have to take a moment to think something up. This results in a pause, usually right before the lie itself, while they desperately reach for something other than the truth. Careful questioning will reveal variations in their story, as a consistent fiction is hard to remember, whereas actual events are usually easy to recall.

Thats the things to look out for to tell if someone is lying or not!!!