As a part of your situational awarness, be sure to look for, and recognize cover! It's one thing to spot a threat, it's another to engage in a gun fight. Be aware, cheat, but win! Always shoot from behind cover if possible.
Coming out of a grocery store one time, I noticed two men, one standing on the left of the doors, and one standing on the right of the doors. I stopped, and checked them both out really well. As I did this I noticed another man standing beside a pickup in the parking lot, about six vehicles down. I moved a very short distance so other folks could get out of the store, but kept an eye on all three men. I then moved over to the nearest car in the lot, got between it, and the one beside it. Cover. I smoke, so I took the time to light up, while watching them. After a short while the guy by the truck made a sign to the others who then went to the truck, they all got in and drove away. I didn't move untill they were gone, and I was keeping an eye on the rest of the parking lot as well.