One important way is to train to a level of subconscious competence (John Hearne calls it "automaticity") so that your shooting tasks aren't cognitive skills requirements. In essence, as John Helms or Scotty Reitz characterized it, you're "problem solving with a pistol". That means you're in a cognitive, not emotional mode, during the encounter and are conscious of the background and surroundings before and during the encounter. You should "war game" it every day as you move about. For the next several weeks, several times a day, pick out a location and see a deadly encounter there. Look at the positions of advantage, cover, light, terrain, traffic patterns, etc. and see what problems are presented and how you'd deal with them. You'll see those background problems more clearly and more reflexively. You can set up static problems on the range with no shoots, surroundings issues and background problems and work them. Start out static and then do lateral movements around the problems to gain more advantage, to clear surroundings and background issues and just because it's likely you'll move during an encounter. Oh...and don't muzzle those no shoots as you move and as you move the gun around. That's a whole new world of consciousness for many folks.