I've done hundreds if not thousands of building searches and would like to bring up a couple points you might want to incorporate in your training.
Mirrors: I carried a small mechanics inspection mirror in my jacket pocket. I like the one with the extensible or telescopic handle. I used it to peek into rooms prior to entering.
Learn to shoot with both hands, one at a time. forget the two handed grip for hand guns. It means less exposure. You can easily check this out by standing behind your barricade. If you are on the right side of the barricade, use the gun in your right hand, if on the left side of the barricade, use your left hand. Try it, (right side) poke your gun toward the target with your right hand, then poke your gun at the target with your left hand. See which hand exposes more of your body.
Get low. If you watch others search buildings or rooms, at they peek around a corner they are always high, standing or kneeling. That's where bandits expect to see you. Lay down, get as low as you can before you peek into a room. Never peek into the room at the same spot.
Something I didn't have until I retired was laser sights on my revolver. Combined with the mirror I mentioned above, I found you could engage targets without exposing anything but the mirror and the revolver.
Simply hide behind cover, stick the mirror out until you see the target, then poke the revolver (or pistol) around your cover and look through the mirror as you put your "dot" on the target.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071