Observe (The first phase of the OODA Loop).

We're talking about an action strategy developed by USAF Colonel John Boyd.  
Observe ---->  Orient ---->  Decide ----> Act

You bring into any situation your history, which serves as a filter for how you observe an evolving situation.  Observation is something that you can practice daily, like a mental game.  Fine tuning this skill of focusing your mind on details around you can help you in the event of a real emergency by quickly processing through the observe part of the OODA loop.  By observing, Boyd was talking simply about your ability to scan the environment and gather information from it.

In an emergency, decisions are made split second.  Human reaction time is defined as the time elapsing between the onset of a stimulus and the onset of a response to that stimulus.  We process approximately 80% of the information we receive with our sense of sight,  but we can and do make observations with our other senses also.

 In the recent box office hit movie Taken II, Liam Neeson's character was blindfolded by his abductors and taken on a car ride.  During that scene in the movie, he processed an incredible amount of information by observing distance (in seconds by listening to clicks of his watch) and sounds (such as the clucking of birds) that he later used to orient himself.  While they took huge theatrical license with this scene, it's the impression of observation that we can bring back to the OODA loop.

We'll link to one source for how to sharpen your observation skills here.
Their ideas include :
1.  Meditation - to learn how to clear your mind and focus
2.  Practicing Logic - using puzzles and other tools to increase your logical reasoning
3.  Practicing Memory Recollection
4.  New Experiences
and
5.  Trial and error of your observations and memory

The point for this opening step of the OODA loop is to make a conscious effort to improve your powers of observation.  The faster you can observe details, the quicker you will move beyond the observe step to the orient step of an emergency situation.  

Here's a cool 42 second awareness test to get you started on your path towards greater situational awareness.

Next up we will be talking about orienting what you have observed.   

Observe ---->  Orient ---->  Decide ----> Act