Upon entering, you'll find a few enemies in the initial hallway. Use the door to stun the first enemy, then quickly dispatch him. Grab his weapon. Proceed cautiously, peeking around corners using Shift. There's often an enemy patrolling the main corridor. Consider throwing your weapon at him to stun, then follow up with a melee kill. In the rooms, prioritize enemies with firearms if present. If you encounter multiple enemies, try to lure them into a choke point or use a thrown weapon to create an opening. Remember, you can pick up any weapon an enemy drops. execute downed enemies for extra points and to ensure they don't get back up.
