One of the most important observations you can make in relation to the hands is noticing when they go dormant. When the hands stop illustrating and e… - Joe Navarro

If you wish to enhance your effectiveness as a persuasive speaker — at home, at work, even with friends — attempt to become more expressive in your use of hand movements. [...] Whether you naturally speak with your hands or not, recognize that we communicate our ideas more effectively when we employ our hands.

When we press our lips together, it is as if the limbic brain is telling us to shut down and not allow anything into our bodies, because at this moment we are consumed with serious issues. Lip compression is very indicative of true negative sentiment that manifests quite vividly in real time.

When confronted with mixed signals from the face (such as happiness cues along with anxiety signals or pleasure behaviors seen alongside displeasure displays), or if the nonverbal facial messages are not in agreement, always side with the negative emotion as the more honest of the two. The negative sentiment will almost always be the more accurate and genuine of the person's feelings and emotions.