How do you improve your perception/Situational awareness?

Not sure if you're talking about the military, but in psychology, you can do that by consciously placing yourself in the environment. Focus on the task at hand, do not let any other conflicts come into mind unless relevant. When you consciously feel that you're in the environment, consciously look at the surface then analyze situations on the spot, consider the possibilities and alternatives of an event, and again, consciously place yourself in that spot. (Start on the top, move inside.) Do not drift into the thought of "I'm just here." drift into the thought of: "I'm here, this is what's going on, and this is what's here." As for perception, the best way to handle this is to abandon your bias. Perception is purely psychological and unique to the individual. If you allow your bias to come up, then every time you see the stimuli you will associate it to your past experiences. But if you treat it as a new experience and use logic, you may be able to reach the conclusion that you might be able to trust so and so, or that x will not cause Y to happen in this situation. However, bias can be good. Bias helps you perceive an event because you've grown to accept that X happens because of Y or in association to Y.