Just generally be aware about your surroundings. It is proven that most attacks occur at the victim's house, and 86% of these are by people who are known by the victim. We're not saying that you have to spend the rest of your life on edge and not treating everyone as a potential killer, but you do have to be wary about your surroundings.
One of the most vulnerable positions that you can be in is at an ATM. Research has shown that as you have your back to everyone behind you, it makes you an easy target. Whilst retrieving your money, every few seconds look around to check out your surroundings.
If you suspect notice any suspicious activities around you look for shadows that may reveal someone hiding around the corner waiting to surprise you. If you spot someone near you, and if you're quite a distance away, stop and listen. If you're right there, don't turn your back, but take steps back slowly; then if it is an attacker, turn your back and run.
If a situation feels uncomfortable, remove yourself from it. For example, if you don't trust a particular person, don't hang around! Go with your initial thought about this situation, and trust your gut feeling.
If someone has a knife strategically placed on your neck or groin, listen to them and don't risk being defiant. Your main arteries are located in your neck and groin, and if they cut those arteries, you will be unconscious in eight seconds, and dead in thirteen. Wait until they have removed the knife from those areas before attempting to fight back.