These nonverbal cues have been proven to turn people from a state of ambivalence to agreement with what you are saying to them.
The best part is they won’t realize that your nonverbal cues are the reason they agree with what you say; they will think that they agree with you because the content of what you’re saying is good.
When you need someone to agree with you, simply nod slightly while talking to them.
Whenever you mention your product or service, smile! This will trigger an empathetic response in others, causing them to feel happy and associate your product or service with that happiness.