People use many different facial expression when engaging in conversation. Some believe that the same emotional facial expression is universal between people. A study was done in 1990 by Silvan Tonkans and concluded that the facial expression deal with the emotional state of the person. You'll need to spend a bit of time studying different facial expression in order to understand them. This way you can learn to recognize the 7 most common facial expressions. Afterward, you will start to understand how facial expression work and be able to identify and recognize other facial expressions. Here is a great article about the different facial expression with images and details about what to look for. Study these images and try using them next time you are speaking with your friends. https://www.wikihow.com/Easily-Read-Faces-and-Facial-Expressions