Stealth Technique
Hold-Ups
to pull out your gun and perform a hold-up. While in a hold-up, you can point your gun at an enemy's critical points, and they may relinquish items. Keep your guard up; if the enemy finds an opening during a hold-up, they can launch a counterattack against you. You can also perform a hold-up on an enemy by pulling out a firearm after throwing them on the ground with CQC.
Looting Items
Search unconscious, sleeping, or dead enemies to find item boxes on them.
Press while your hands are empty to pick up a body, search it, and put it back down.
Tactical Reloads
You are defenseless against enemy attacks while reloading a firearm. Press 
twice quickly to switch out magazines in a short amount of time.
Watch your ammo while using a firearm, and time your tactical reloads accordingly.
Jump-Out Shots
While against a tree or a wall corner, press with a gun in hand to jump out from cover and ready your weapon. This allows you to switch quickly from hiding to attacking.
Grenades can be thrown while you are peeking from behind cover.
Hanging – Drop and Catch
If you are hanging and there's a level below you, press 
to let go, then press 
at the right time while you are falling to hang on the level below.
This will help you move to lower levels swiftly.
Using Enemies as Shields
While restraining an enemy in CQC, press to use them as a shield, discouraging other enemies from aiming at you. You can use this opportunity to launch your own attack and escape before you are overwhelmed.
Hold or 
to keep holding on to an enemy for a set period of time while you have them restrained in CQC.
Interrogating Enemies
Press 
while restraining an enemy in CQC to threaten them with a knife to get answers.
Enemies can give up hints or other useful information. Some information can only be gained from interrogations.