Various Gameplay Hints
Use your handgun's secondary fire (on-the-left-shoulder-button) to briefly disable lights rather that shooting them. Your enemies will be less suspicious. Body are a foolproof free gift that a tricky spy is on the loose. Relocate them into spaces that guards aren't patrolling to remain concealed. The 2 bars up leading represent your exposure and volume. Remain in the dark, and relocate gradually, to stay clear of being found. For a simple kill, sidle up against a doorway and utilize your whistle to draw a guard over. Jump up and stab them in the trachea once they walk however.