Observe

We may establish many good habits in our life or bad ones . It doesn't matter if you learn to observe people well you'll influence many more than normal.

Have you seen Thomas Shelby he is the one with best observation skill. He watches people and say there are lying or not in a minute . If you start to observe in few days you'll get a hang of it . 

What you need to do is record every moment or every geasture of upper and lower limbs very carefully. And write them down . 

Each movement in human body is base on limbic brain response. Words may lie but body won't . Specific movement involve specific message and if you decode the message they are sending by their limbic response. You can soon come to know how that person is feeling and you can approach him in that way .