You can get this one in mission 11, Captive. After you’ve escaped your prison cell and freed your fellow prisoners you will make your way towards a warehouse where your brother is located. On top of this warehouse is a Sniper, he does have a very strong tell-tale red guidance laser, making this one quite simple, move from cover to cover nice and slowly. The Sniper will need a clear line of site on you to be able to shoot you, deny him this and you’ll have no worries here. If you do get shot by the Sniper, simply reload your last checkpoint and have another go. Once you’re in the warehouse, kill the Sniper to unlock your achivement.