Click Right Analog-stick to zoom in with a sniper or rifle. This will not work with large automatic machine guns.
If you are running and are suddenly fired upon, click the Left Analog-stick to lie flat.
Quickly press A to reload your weapon.
Quickly press B to switch to your alternate weapon(s).
Quickly press Y to lean up against a wall or some sort of cover in third person view.
Slip and slide
When you are running and suddenly get fired upon, quickly tap the Left Analog-stick. You will slide along the ground. If you are running and click and hold the Left Analog-stick, you will do a sort of belly flop and slide on your stomach.
Sluggish controls
If you are carrying a large automatic weapon, the controls will feel sluggish because of the weight of the gun. However, if you switch to a hand held gun, the controls will be more responsive.
Walls and barriers
You cannot hide behind walls or barriers in first person view unless you plan on staying at that location for awhile. Unlike third person view where you can just tap Y to automatically hide, you must hold Y in first person view to hide. Press Up to look over a barrier or to open fire. Press Left or Right (depending on how you are positioned) to look out.
Warfighter difficulty
Successfully complete the game to unlock the Warfighter difficulty setting.
Xbox Live music help
Keeping the music on is recommended, as the tempo picks up when you are approaching the enemy. Conversely the music slows back down when you are at a safe distance.
Quick tips in battle...