Verbal and non-verbal communication vary widely from culture to culture. Something that feels positive to an American, such as making eye contact or offering an encouraging hand gesture, might be taken in an entirely different way in a different country. Pitch, volume, and pacing of speech also take different forms for different people.
Americans traditionally greet by shaking hands. A strong handshake is considered a positive thing. In many Asian and African cultures, a non-contact greeting is preferred, such as a bow or bringing both hands together in front of you as if in prayer. Asians and those from the Middle East prefer a soft handshake to the traditional firm American grasp. The 'A-OK' hand sign (thumb to index finger) is a positive in America and an insult in many European countries.
In America, it's a sign of respect and honesty to make direct eye contact with everyone. In Asia, it's considered rude to make that kind of eye contact with those in authority or one's elders. Westerners consider facial emotions to be a good thing. In the East, a smile might not indicate happiness. It can be a signal that you have been misunderstood or to hide embarrassment.
People from Anglo-Saxon countries wait their turn to talk if they've been taught their manners. Interrupting is considered rude. In many Latin cultures interrupting is not rude and is expected. Asian cultures often take the wait-your-turn rule to extremes, giving a pause before responding. Pitch and volume also differ between cultures. Americans, for instance, usually speak with a low pitch and only raise their voices in anger or excitement, while the Portuguese speak in higher pitches and volumes during normal conversation.