Read emotions through facial expressions

Familiarize yourself with the neutral expressions of the significant people in your life.
Knowing their neutral expressions will help you identify any changes.

Be vigilant.
Most purposely shared facial expressions last for just about 10 seconds, so you have to watch closely to not miss a thing.

Read multiple emotions simultaneously.
People always feel multiple emotions at once, resulting in a confusing mixture of feelings on the face. Once you read these emotions, you can tailor how you communicate with them. For example, a person might be smiling through the mouth while simultaneously portraying sadness through their eyes.