Some people have an inherit lack of skill when it comes to driving, maybe you are one of them, or maybe not. But protecting ones self does include safe driving and awareness behind the wheel. There was a time when I was experimenting with "situational awareness" while I was driving. This is dangerous therefore I have come to the conclusion not to worry about it to much, as you could end up distracting yourself from the road and therefore getting in an accident.
Best bet is to follow the basic rules explained in your basic driving instruction, keep your eyes on the road, check your mirrors, and keep attention several if not even more car lengths ahead of you.Do keep any eye open but don't try to get the make and model of every car around you, you will miss the big picture, driving.
Keep an eye out for different things, swayed driving cause then someone could be impaired or having a conflict in the vehicle, driving too far under the speed limit is a good sign of impaired driving as well. If you see such things and anything else that stands out, then you should get the plate #, make and model, color, and location. Remember to always know where you are and where you are headed. If you call the police at anytime, they won't be able to help without that information being accurate.
Don't get me wrong, you should have situational awareness behind the wheel, but don't try to hard or you may over look potential dangers, look for the "right" things, worn tires, loose wheels, sparks under cars, loos loads of cargo etc... all of these things can be dangerous to you and everyone else on the road and should be addressed to prevent injury or death.