Nonverbal behavior is itself complex since all people are different and present themselves differently. Reading body language can be challenging because when interpreting the signs people are sending you, you need to take into account the whole picture. For example, did that person already mention to you today that he had a fight with his wife or didn't a get a promotion at work? Or was he visibly anxious over lunch?  When interpreting others’ body language, it’s important wherever possible to take into account their personality, social factors, verbal behavior, and the setting. While this information is not always available, it can be helpful to read body language. People are complex, so it shouldn't come as a surprise that how they convey themselves with their bodies is complex too! You could compare reading body language to watching your favorite TV show; after all, you wouldn't just watch one scene in your favorite TV show, but the whole episode in order to properly understand the meaning of that one scene. You'd also probably keep in mind past episodes, a character’s history, and the plot as a whole. You need to look at this bigger picture also when it comes to reading body language! There is no 'one size fits all' when it comes to body language. If you are invested in being able to read a person's body language accurately, you may have to 'study' that person for some time. What is true for one person may not always be true for another. For example, when lying, some people break eye contact, while others attempt to maintain even more eye contact than usual so that they won't be suspected of lying. For some emotions and expressions of body language, the meaning of the messages is culturally-specific.  For instance, in Finnish culture, when a person makes eye contact, it is a sign of approachability. By contrast, when a person makes eye contact, it is considered to be an expression of anger for the Japanese.  To give another example, in western culture, a person who feels comfortable with you will lean...

TL;DR in Indonesian:
Ketahui bahwa membaca bahasa tubuh adalah hal yang kompleks. Ingatlah untuk mempertimbangkan perbedaan yang dimiliki setiap individu. Sadari bahwa ada perbedaan bahasa tubuh berdasarkan budaya. Perhatikan bahwa penafsiran akan berbeda menurut saluran nonverbal yang digunakan.