These include shaking head, eyes narrowed, scowling, frowning. Body language is more meaningful when several expressions take place at the same time. For example, the combination of leaning forward, nodding, and smiling is a strong indication of agreement and openness. Most meaningful is a matched set of gestures that agree with what the person is saying. As a rule of thumb, individual body positions or movements are frequently meaningless.
Some faces form a smile or a frown more naturally than a neutral expression.
What is meaningful, however, is a transition from one body position to another. If a person spends the entire meeting leaning forward, that may be just comfort. But if the same person starts out leaning back and then gradually moves forward as the meeting progresses, that's non-verbal communication. From the moment you greet the customer, observe his body language. At the beginning of the meeting, it is normal for customers to appear somewhat reserved or nervous.