Studies show that body language accounts for over 50 percent of overall communication. While most of us focus solely on what the other person is saying, we're ignoring most of what they're actually trying to communicate to us. Certain things to watch from the other person are: where their feet are pointed (wherever they're pointed at is who or what they're focusing on), crossed arms, which can be a sign of being closed off, or hands on their hips, which signals a more open stance. If their hands are behind their back, that could be a sign they're also anxious!
Be aware of your own body language signals as well. Use mirroring techniques such as imitating the other person's movements to show a sign of trust, and keep eye contact (or fake it). A trick my father always reminded me to use is to stare at the bottom of their forehead since you can't look into both eyes at once — it has the same effect. If you forget everything else in the moment, just simply complement them and smile!