Like the Japanese custom of bowing, the hand–shake is very important because it is part of the first impression that people form of other people. Japanese have a general reputation for giving a rather weak, unnatural handshake, and this creates and unfortunate impression.
The handshake should be neither weak nor aggressive, but firm, warm and brief (3–5 seconds). One uses the muscles of the whole arm, not just the hand. While shaking hands, it is important to look directly into the eyes of the other person with a pleasant smile.
If one mimics Japanese politicians who shake hands and bow at the same time, eye contact and facial expression are lost. If one meets some–one for the first time and shakes the person’s hand covering it with the left hand, it seems an exaggeration of friendliness, and will cause the other person to feel uncomfortable.