The first and fundamental foundation of personal safety and security is to KNOW that trouble can emerge at any time; it can pop up out of nowhere and appear suddenly.
Knowing this to be a fundamental principle, you can train yourself to be alert and to be ready – a subconscious alertness – while not interfering with your day-to-day lifestyle.
For fundamental situational awareness,
The two things that you need to ingrain into your mental alertness are:
Source: News To Me