If you press your reload button before performing an action (opening a door, rappelling, talking, pressing buttons, dis/arming bombs), you won't have to wait for the animation.

Before falling down, press your roll button. It's a bit of a faster drop (or rather, it gets you further along).

Ammo conservation

• You can ignore a lot of enemies e.g. all but 1 London on-foot enemy.
• Most enemies will have a grenade spot in Focus Aim that you can shoot for a one-shot kill. You can also hit this spot with a sniper.
• Try not to use too much special ammo (though you should use it on Station T helicopter and possibly Train Red Grant), Armor Piercing ammo (though you should use this on the Factory tank) and Sniper ammo (aside from when you're required to use the Sniper) - it's best to leave them for Red Grant at the end.

London

• You can pretty much ignore every enemy on-foot aside from the one that gets in the way of the room with the keypad to get the Passkey.
• Get the schematics at the end of the Passkey woman's room
• Switch to rockets when ascending in the jetpack to shoot down the first two rappel enemies, switch to machine gun and shoot the enemy on the right-hand side, then turn right, target and shoot the jetpacks.
• Shoot at the heli, and stay relatively close to Big Ben so the heli stops as soon as it's up, then switch to rockets and keep shooting, moving slightly to avoid rockets and to manipulate the helicopter to stay where it is.

Hedgemaze

• After radio cutscene, go right and over the wall for complex schematics
• After the radio enemy (you can ignore him), go right after passing through the gate, climb the wall and roll off it and get the key.
• There's a part a little later on where you can jump over small hedges rather than traverse through gates.
• After passing the last key gate, you'll need to disable all the enemies to be able to trigger the next cutscene. Start by taking down the enemies on the right, then go towards the bridge while turning around to shoot down the other enemies before the bridge, then turn and shoot the barrel by the car to kill the enemies behind it, then move up to the mansion.
• Kronen SMG is very helpful when mowing down the two waves of enemies that come out of the mansion, but make sure you don't empty your clip before triggering the cutscene, otherwise you'll get stuck reloading in the terrorist situation for a couple of seconds.
• In M's room, search the bookcase for schematics
• You can headshot the robots with Focus Sight.
• Kronen SMG is again very helpful, this time in the bomb room. You can easily shoot down all 3 robots in one clip.

Istanbul Pt. 1

• Just a couple of corners after entering the main area (when the Destroy the Russian Garage objective comes up), turn right to go straight towards Kerim's garage.
• Try to turn yourself around inside the garage so you can drive out of the garage and go up the hill straight away.
• The Russian Garage takes 7 rockets to destroy.
• You can just about get away with ignoring the on-foot enemies (do some good rolls to avoid bullets).
• After the first few enemies, rappel down and go left into a building for complex schematics.
• On the second lot of enemies, after rappelling up, roll just after a second of walking, otherwise the scripted explosion will knock you back.
• After the various enemies including shotguns, roll down the ledge and then rappel up. If you're low on health, get the armour before rappelling through the window.
• Kill the three enemies in the room, then move to the turret and destroy the tank (don't bother with any other enemies).

Armour upgrade

Station T

• After climbing the wall and dropping down (might be best not to roll off this one), get your Q-copter out straight away to avoid a cutscene.
• First hostage is when you enter the building.
• Go to the left-hand stairs and diffuse the bomb. Get the schematics on the desk on the right when you exit the bomb room.
• Go to the right-hand stairs and save hostage; proceed to main room.
• Go right and go down the rappel wall, kill all 6 ground-floor enemies, then go right and diffuse bomb at a pillar (killing the enemies means you won't get stopped when trying to diffuse the bomb)
• Go left from there and follow the perimeter, diffusing 2 bombs (one in a room, one at a pillar - kill all 4 floor enemies beforehand)
• Go left from the pillar, then right, and use the Q-copter through the vent, then save the final hostage; get the schematics in this room, behind the crates.
• Go to the room opposite and defuse the final bomb.
• Climb the rappel wall to the right, and go left to get to the newly-fused bomb.
• Before leaving to face the helicopter, go to Inventory and switch all guns to Sp. Ammo.
• Defeat the helicopter with everything you've got, starting with shotgun. Move towards the bazooka if needed.

Istanbul Pt. 2

• After the hill and the gate at the start, turn left. You can turn just before going off the peak of the hill to rotate left in the air.
• Switch to Kronen for the ambush, and make sure you don't kill the last enemy until you get to the car; this way you can get into the car and go after the red car asap.
• Where the red car goes is completely RNG; ideally it'd go right and then left at the junction so you're right by the Checkpoint when you destroy it, but it doesn't do this most of the time.
• Be very careful in the on-foot section; you can die easily (maybe an armour upgrade should be factored into the run). Kill any enemies on the other side that are shooting at you, as well as the Commando enemy, and any others that are constantly 'shooting you off' the controls.
• After the boat goes down, go over to the cupboard to get complex schematics.

Armour upgrade

Underground

• When James says "Kerim, here they come" aim to the right to start on the gears. After going left, then right, before going left again, aim to the left to start shooting at the gears (before passing the pillars, you might be able to break one of the left-hand gears(.
• If you're quick enough and don't trigger the enemies too soon, at the beginning of the on-foot section, you can have an enemy open the door for you to go through.
• You can ignore the Commando and rappel straight up, as you're invincible during rappel time.
• Kill the Commando with the jetpack (use rockets, also use rockets for the 4 enemies in the next room).
• Use the dodge-boosting with the jetpack to get through the last section quickly (use the minimap to help guide you past pillars and to the tunnels). You might need to stop at the landing in the first main area (on the right) to get a new jetpack.

Gypsy Camp

• You can Focus Sight on the turret enemy and set off a grenade.
• Go backwards from the bench and rappel up the barn. Rescue the hostage there.
• After getting a mask, go left past the wagon and rescue the hostage behind the wall (use the barrel to kill some enemies).
• If you go building then cave, make sure to leave the building the back way, through the door at the end of the room you rescue the hostage in. Then follow the stones down and drop to the right.

•   However you can go cave then building; there was hardly any time difference between the two ways when I timed them.
  

• After getting the sniper, go back across the wooden bridge and climb over the wall; this is probably the best sniping point.

Sniper Alley

• Roll off the wall and avoid the enemies.
• A little later on, just ignore the enemies and rappel straight up.
• Use Magnum (if you have any bullets for it) on the Commando to take him down quickly.
• Before triggering the cutscene, get some ammo from the box.
• With the helmet enemies, you can shoot their hips to get a grenade shot. They take two shots to kill otherwise (unless you get a perfect headshot that doesn't hit their helmets).
• Shoot at the helicopter when it arrives; it won't take long to destroy.
• During the cutscene where the billboard mouth opens, you can aim at Krilencu and kill him. If you take too long, the end of the cutscene will reset your aim.

Consulate

• Use a Q-copter as soon as you enter the control room with the first vent (after the first two enemies). Under the archway should be good enough.
• You shouldn't need to worry about Q-copter health for the second vent, as long as you avoid the steam.
• Use the Magnum on the Commando, then the vault locks, and then whatever left on the second Commando.
• When leaving the room with the last Commando, wait at the start of the corridor for a bit - if you go too far ahead before Tatiana follows you in, the enemies won't spawn and so the doors won't open.

Istanbul Pt. 3

• When reaching the first junction you have options for, you should go left into the Russian Garage/Checkpoint area and aim to have 10 kills on the counter when you leave (there are many triggers for enemies in that area; just drive about and you should get them)
• Go back to the junction and down the other way to Kerim's garage. On the way you should aim to kill all the enemies, including braking for ones that sneak up behind you.
• Continue on to the next area, but leave soon after as it usually only has 1 enemy, but going there will allow more to spawn on the way back
• You should have at least 23 kills by the time you come back to your garage, and when you go on, a truck should come sliding out (sometimes it won't for some reason). Destroy that and a few more until you reach 27 or 28.
• Go back to the 1-car area (if you're on 27, another car should come around on the way) and the final two enemies you need to destroy will be there
• Finishing the objective here is the closest you'll be to the gate that opens for the next objective, which is on the left

Train

• At the start of the henchman waves, move behind the doorframe; here you can hide from a lot of Commando bullets while still being able to shoot him.
• Kronen is very useful after Commando for the rest of the waves. Run to the Commando's end to spawn more, then walk back to the other side while killing the new enemies so more spawn on the Commando side, and repeat until the end. This is a good place to pick up ammo.
• Target when you start moving on the platform and shoot the shield enemies as they run (Focus Sight helps; also helps when they stop).
• Focus Sight the RPG launcher on the platform and shoot his shoulder.
• During the cutscene after the first lever, you can move - use the minimap to guide you out of the left-hand exit towards the next room
• From the platform you're on from the left-hand exit, shoot down any of Tatiana's attackers on both sides of the block (if you're lucky, you might be able to get the key and then take them down when going down the stairs, but this is much safer).
• A Briefcase Turret by the train tracks is very useful on the turret section.
• Run over to the turrets and use the shotgun. It's a three-shot kill.
• Before fighting Red Grant, go to Inventory and switch all guns to Sp. Ammo.
• When fighting Red Grant, Focus Sight straight away and shoot at the little symbols that come up to make him vulnerable. You can continue to combo this until the end (be wary of ammo - the game might switch you to an unloaded Magnum, which will give you no chance to combo).

Factory

• Dodge-boost through the first small room.
• After landing the jetpack the first time, don't go to the immediate door into the lever room, go along to the door further on, just so that the enemy won't be in the way.
• Kill the jetpack enemy, and then land and kill the rest before the first bomb.
• After killing some enemies behind the fence, you can try to control the crane (even if there are still some enemies further on).
• Serum Gun might work in the warehouse while you plant the second bomb.
• When leaving the warehouse, roll down from the crates.
• When going down the elevator in the final bomb area, throw a grenade to the right, towards the glass where the tank is. If you've done it right, the grenade will blow up on the tank as it moves out. It's untested whether this actually damages the tank, but it's worth the 'risk'.
• Ignore enemies in the second warehouse visit; just go straight to the lever.

Border

• Serum Gun might be useful when getting the Dock Key.
• This boat drop is much easier than Istanbul Pt. 2; you can pretty much just keep bringing it down even if you get shot once or twice.
• At the end, aim at the left of the opening between the barrages where the Assault Boat appears. You should be able to one-cycle the boat; when you defeat it, you'll be right back in the middle to drive off straight away.

Octopus Base

• Entering the first area with the tram, press Target twice so you target the enemy on the farther side, and kill him before he gets to the door. This skips needing to destroy the keypad.
• On the tram, you can either shoot enemies' grenades, or circle inside the tram to avoid bullets.
• Take the top route first (the door up the right-hand stairs when you rappel down) - it goes on for much longer and you're likely to get shot a lot, so it's best to have the most health through this part. There's no time difference between going to either, it's just health management. However, if you go bottom then top, then going back to the main room to go to top will have more enemies, a couple of them in the way.
• When getting in the jetpack, switch to rockets early and target Eva during her laugh cutscene to get a few rockets in before everyone starts shooting at you. Also, start moving forwards towards her so you're closer to the landing zone.
• If a normal enemy is near a shield enemy, Focus Sight his grenade. This should double-kill.
• It may be worth taking out the RPGs on the second jetpack ride, otherwise they'll be in the way on the walk back.
• On the bottom route, you can ignore the lower enemies from the top route's silo part. They won't shoot when you disarm the warhead. - Red Grant
• It takes about 24 standard sniper bullets, 3 Q-copters and 4 APR bullets combined to defeat Red.
• Start with the sniper, then the APR. If you need more, use the bazooka or Magnum (shotgun's kinda crap here), and then whatever else you have.
• While you hide away from Red's attacks, send out a Q-copter and self-destruct right under his cockpit (steady, now).