Hold Shift while zoomed in with right click to hold breath and steady aim

Switch between fire modes

Inspect your weapon and look for your firing mode

Open inventory

Take out the mag and estimate the remaining ammo

Look into the chamber to see if there is a bullet

Quick reload. This will toss mag on the ground for a quicker reload. Do not forget to pick up your mag afterwards

Selective reload

Toggle flashlight

Toggle laser sight

Switch reticles in your red dot sight

Switch between stacked sights / scopes

Throw grenades

You can drag and drop items from your tactical rig or pockets onto your quick access bar (keys 1 through 0), this also applies to grenades

Select a grenade from your quick access bar (keys 1 through 0) to take it into hands to be able to time your throw

See the remaining time of the raid and get a feel for if it is still worth to check on the early objectives

Sprint (make sure Hold to Sprint/hold breath setting in Settings > Controls is enabled)

Crouch

Go prone. When prone, return to your previous stance

Move through your stance from standing to crouching to prone

Instantly go to minimum speed. Press again to return to your previous speed

Lean left

Lean right

Do a slow left lean

Do a slow right lean

Blind fire above you

Blind fire to your left

Fold / unfold your stock

Quick melee attack while holding a firearm

Lower your helmet visor

Mumble, if AI is nearby, they will respond to you with a voice line