Hiding Your Poker Tells

As everybody knows, poker is a combination of skills and strategies, which means when we play poker, we should not only pay much attention to skills but also we should also know psychological factors.
A professional poker player could know what you have in your hand by observing your facial expression, some unconscious movements or whatever. So what we should do is to hide your poker tells as much as possible.
Following video would let you know how to hide your poker tells.