The concept of Safety is paramount in self-defence.
Plain common sense is essential for personal safety: being aware of surroundings, knowing who to call or where to go if feeling threatened (especially for younger people), and how to defend if necessary.
One of the most important skills is situational awareness – knowing what’s going on around you. Simple in principle, but it requires some practice. Situational awareness is really just another term for mindfulness, knowing what to look for, and then putting those observations into context so as to know what to do with the information.
Practise by keeping your head on a swivel and using all the senses to take in your surroundings; a lot can be learned from the sounds (or lack thereof) and even smells in an environment. Stay relaxed to ensure an open focus, allowing more information to be absorbed. Research shows that when nervous or stressed, our attention narrows.
Place yourself in a position for optimal observation. For example, find a place where all or most of the exit points can be seen, and that allows for your back to be to the wall.
Be aware, especially of things like comfortable/uncomfortable or interested/uninterested behaviours of people (and how that fits in with what others are doing), notice peoples’ hands to ensure they are not concealing a weapon or preparing to strike (hands often telegraph hidden nefarious intentions).
Finally, look alert (keep your nose out of the smartphone!), and have a plan about what you will do if you need to act. There is no need to be paranoid, just be mindful.