Call of Duty: Modern Warfare 2

The Only Easy Day...Was Yesterday: Make sure you watch your fire because there are many explosive barrels with C4 and many civilians. Take it slow and kill the enemies. When you do a breach, make sure you're hitting enemies and not civilians. At the end of the mission, you will need a thermal scope and enemies have them as well so stay in cover. Once all the enemies are dead, proceed to the last breach.

The Gulag: You start off with sniper fire from the helicopter and later you will land in the facility. Go inside, pick up some weapons and get ready for close quarters combat in the facility. As you progress through the mission, you will reach a part where Ghost says: There is a bathroom through this wall, you will plant a breach charge. Breach in, use the grenade launcher in the back and knife the others. You can try and fight, but I just used flash bangs and ran in. Once you drop down the hole in the final room you beat the mission, even if you didn't kill one enemy.