This is a vitally important area of study and can mean the difference in surviving both a physical and legal encounter. “You don’t have to be right, you do have to be reasonable”. If you don’t understand the legal meaning of the aforementioned statement, you are at serious risk.
The linked article also delves into the science of proxemics. The article should be viewed as a motivator to seek training, not a substitute for. There are many other Pre-Attack Indicators not mentioned; a great source that covers the subject well is Mas Ayoob’s book (Deadly Force).
I believe the most important point covered in the article is the manner in which a person approaches. Don’t hesitate to act if someone is approaching at a “Targeting Pace”.