There is a variety of guides on the net that supposedly guide you through the Metro 2033 Redux Ranger achievement. I, however, found most of them lacking. For example, the IGN wiki-guide tells us there is a total of forty-seven (47[!]) Ranger caches, and that you need to catch 'em all. At the other side of the spectrum is the 100% Achievement Steam Guide, which only contains some vague guesses.

I found the Metro Fandom wiki (https://metrovideogame.fandom.com) to have the most complete and intelligible list. Hence, I took it as a starting point for writing this guide. I did not come up with all the stash locations myself. All credit for the locations of the caches go to the Fandom wiki. However, the biggest problem with that guide is that it is text only, which severely hampers your ability to check whether you are indeed at the right spot.

To remedy the situation, I used the list and descriptions on the Fandom wiki and supplemented them with my own deliberations and pictures from my own playthrough. Hopefully, an achievement guide in this form serves a niche and is of added use to all those who are trying to unlock the Ranger achievement in Metro 2033 Redux.

1. The location of the caches is different between Metro 2033 Redux and vanilla Metro 2033, thus reading an original Metro 2033 guide is no use. Incidentally, this guide is of no use for players of the original Metro 2033.
2. You don't actually need to take anything from the caches. Just being in the room/spot/vicinity of the stash is enough for it to register.
3. A stash or cache is something that is deliberately stored away—dead guys and their loot are not a cache/stash so you don't need their goodies for this achievement.
4. Thus, a lot of stashes in Dead City show signs of human activity. E.g. they are guarded by traps, or an arrow is pointing towards it, or they are accompanied with subtle graffiti left by its former owners.
5. I'll also be covering all three safe locations in the chapter (counts towards the Thief achievement), the location of the diary entries (needed for the Blogger achievement), and as a special encore, a good location to unlock the Manhattan Project achievement.

1. Orange footlocker on the first floor of the metro terminal, just after the staircase.
2. Safe in a room at the first floor of the metro terminal, at the end of the catwalk.

The first two stashes are easy enough, and can be found right at the start of the chapter. The second stash also contains a safe (counts for Thief achievement) and a diary entry (needed for Blogger achievement).

(Artyom standing at the entry point of the chapter, the catwalk at the upper-left leads to Stash #2)

When starting the chapter, stay on the ground level and go to the room at the far right corner in the entrance hall. Get the key there to open the safe at Stash #2—technically, for the achievement to unlock you don't need to interact with the stash but I assume you might just go all the way—it's hanging from the wall at the back of the room. Once you've done that, return to the hall and enter the staircase just left from where you started (beware for the trap when entering the staircase).

(Key hanging in the storage room, and location of the staircase to the first floor)

1. Orange footlocker on the first floor of the entrance hall, just after the staircase.

The first stash is located directly on your right when you exit the staircase on the first floor. Open the footlocker and grab its contents.

(Stash #1)

2. Safe in a room at the first floor of the entrance hall, at the end of the catwalk.

From the first stash, continue along the catwalk and make a turn. Beware for the tripwire hidden quite conspicuously across your path. Enter the door at the end and the second stash (containing a safe and a diary entry) is yours.

(Stash #2)

3. Safe on the ground floor of the bank, in the vault.
4. Stash with a Tihar on the first floor of the office building, access through second floor lift.

The third and the fourth stash can be found in the second building you enter (it seems to be a bank). There's another safe here (counts also for Thief achievement) and an easy chance to unlock the Manhattan Project achievement.

First follow Bourbon outside. After wandering around a bit, you will get separated from him and have to make your own way through the Dead City. Cross the stream just to the right where you exited the Metro entrance hall, and enter the office building. When entering the office building, you can see a reception area just in front of you. To get the key to the safe for the third stash, you need to enter the front desk.

(The office building containing the bank)

You can do so by jumping on the ATM right next to the lift and crawling through the broken glass panel. In the front desk you can see a dead body with a key right next to him (sometimes the key clips a bit through the ground). The area, however, is a Radiation Hotspot (they degrade your gasmask filters at an alarming rate and also drain your health). So make haste retrieving the key (alternatively, for an easy way to unlock the Manhattan Project achievement, just stay in the room for 60 seconds until it pops).

(Reception area of the office building. The front desk is just across the room, the key is lying within)

3. Safe on the ground floor of the bank, in the vault.

Exit the front desk the same way you entered it, and proceed along the reception area (to the right from whence you entered). You'll come across a staircase, pass it and go through the security gate. To your right should be a room with a safe inside. Enter it for the third stash.

(Stash #3 in the bank vault)

4. Stash with a Tihar on the first floor of the office building, access through second floor lift.

The fourth stash can be located on the first floor of the office building. There is, however, one small caveat. You cannot directly access the room on the first floor through the staircase. Instead, make your way to the second floor and go to the elevator. Notice how it's stuck halfway? And notice the subtle arrow painted on the wall? Jump on the elevator and through the open hatch to enter the first floor. In there you'll notice the fourth stash containing an ammunition crate with a Tihar lying next to it.

(Stuck elevator on the second floor of the office and Stash #4 with the Tihar)

You can only leave the first floor through the elevator shaft. Doing so will return you to the reception area at the ground floor. Exit the office building by going, once again, to the second floor. Make it through the offices and slide down the building at the end.

5. Grey ammunition crate in the back of a delivery truck, just before the playground.
6. Ranger camp with a cooking fire inside a building, just before entering the playground.
7. Olive toolbox in the backroom of a supermarket, just after the playground.

The next three stashes can be found at the playground area. After exiting the office building you will have to turn right. Your path will be blocked by a storage building. Open the door and take care of the Watcher. Exit the storage room and you'll enter the playground area.

5. Grey ammunition crate in the back of a delivery truck, just before the playground.

The fifth stash is located inside the delivery truck on your left side after exiting the storage room with the Watcher. The back of the truck is open and it has a couple of large crates stacked inside. Walk past the crates and behind them a grey ammunition crate is located with the spoils of the fifth stash on top of it.

(Open delivery truck with Stash #5 in the back)

6. Ranger camp with a cooking fire inside a building, just before entering the playground.

The sixth stash is located right after the fifth stash. Just walk past the delivery truck and you will see the broken sign of a barber shop. You can enter it through a small broken shop window. Inside you'll find a ranger hideout containing an oil lamp, cooking spot and an ammunition crate with the sixth stash. There is some ammo hidden on top of the furniture where you entered, you have to jump to see (and grab) it.

(Front of the hair salon and Stash #6 marked by the ϟПАРТА (SPARTA) sign)

7. Olive toolbox in the backroom of a supermarket, just after the playground.

For the seventh stash you'll need to cross the playground. When you do so a cutscene will play. Enter the building at the far side and make your way through it. You'll end up in a room containing a small supermarket. Go to the right, and enter the backroom. Inside there is a grey ammunition box and an olive green toolbox containing the seventh stash.

(Backroom door of the supermarket and location of Stash #7)

8. Red metal toolbox inside the back of a delivery truck that got stuck at the collapsed intersection.
9. Orange lockbox inside a minivan, just next to the stairs past the collapsed intersection.

Exit the supermarket through the shop windows, and follow the stream to the left. You'll come across a metro entrance next to a huge sinkhole. The sinkhole used to be an intersection that collapsed and is now flooded with irradiated water. Someone, however, found it prudent to locate a stash in the back of delivery truck that's stuck at the flooded intersection.

(View of the metro stairs with the stuck delivery truck containing Stash #8 in the center)

8. Red metal toolbox inside the back of a delivery truck that got stuck on the collapsed intersection.

To get to the stash, you'll need to jump across the irradiated waste from a partially submerged car. Narly, isn't it? To make the jump you'll need to shift-run and walk a bit over the hood (that is underwater) of the partially submerged car. It's tricky, but it's manageable. The stash is located in the red toolbox in the back of the truck.

(View of the partially submerged car and the red toolbox containing Stash #8)

9. Orange footlocker inside a minivan, just next to the stairs past the collapsed intersection.

Now jump back on the partially submerged car, and make your way to metro exit across the flooded intersection. Once upstairs, make a sharp right turn and next to the stairs you'll see a white minivan with an open sidedoor. Inside you'll find an orange footlocker containing the ninth stash.

(White minivan located next to the metro exit and Stash #9 inside)

10. Ranger hideout with a tape recorder and grey ammunition crate, located at the end of a hallway to your right just after entering the hotel.
11. Orange footlocker behind a crack in the wall in the basement of the hotel.

Now climb the rubble to your right from where you first exited the tunnel from the flooded intersection. You should be able to enter the hotel through a passageway in a collapsed wall. If you struggle finding it, it's just a bit to the right of where the demon landed and marked with a conveniently large and out-of-place street sign.

(Entrance to the passageway to the hotel, conveniently marked by a large sign)

10. Ranger hideout with a tape recorder and grey ammunition crate, located at the end of a hallway to your right when entering the hotel.

The tenth stash is not too hard to find. Just don't get distracted by that oil lamp with a tripwire trap right in front of you. Instead, when entering the hotel turn immediately to your right and proceed along the hallway. Mind your step for the tripwire trap, and eventually you'll come across a closed door.

(Beware for the tripwire trap in the hallway. The graffiti next to the door leading the hideout reads Открыто meaning "open" in Russian)

Open the door and enter the ranger hideout. It contains a second diary entry (needed for the Blogger achievement) and a tape recorder with a message from Hunter. The tenth stash is on top of a grey ammunition crate on the table.

(Ranger hideout and Stash #10)

11. Orange footlocker behind a crack in the wall in the basement of the hotel.

Now return to the staircase, dismantle the tripwire trap, and proceed towards the basement. You know you're on the right floor once you have to jump down three feet because of a broken staircase. Proceed through the cellar rooms, and eventually you'll end up at a staircase at your left hand. You can go up there, but it's a dead end with some loot.

Instead, the penultimate stash is located in the partially flooded room to your right. Enter the flooded room, and immediately look left, you'll see the small stream comes from a large crack in the wall. Shine your light upon it to reveal an orange footlocker containing the eleventh stash. Watch out for the trap guarding it.

(Dead end staircase and crack in the wall containing Stash #11)

12. Safe in the ranger hideout within a building marked with a stencilled ranger helmet.

So this is it, you almost got the Ranger achievement. First, however, you'll need to reunite with your favourite drinking buddy Bourbon. From the penultimate stash, continue your way through the basement and you'll have to climb up to the surface. Continue along the road and you'll end up at a small passage. Bourbon should be there to greet you with enthusiasm and lead the way once more.

Follow him and after a short hike you'll approach a crossing just past a small building with a bit of iron railing next to it. Bourbon should stop at the corner for you to catch up with him. Don't approach him, instead turn right there. You should see a large broken yellow-and-red sign (saying магазин инти[м]) next to the entrance of a semi-basement. Go down there and pick up the key from the dead body.

(Crossing where Bourbon stops for you and entrance to the sex shop in the semi-basement)

12. Ranger hideout with a safe within a building marked with a stencilled ranger helmet.

Now head up again and from the stairs to the semi-basement turn immediately right. You should see a hole in the wall with a stencilled ranger helmet to the right of it. That's the entrance to the ranger hideout (and the twelfth stash). Go in there, and (if you followed this guide) the Ranger achievement should unlock immediately upon entering. You'll also find the third diary entry here (needed for Blogger)

(The stencilled ranger helmet indicates that a ranger hideout is nearby)

For the stash you need to continue a bit through the apartment rooms. Watch out for the tripwire and make your way to the back where the third safe is waiting for you (counts towards Thief achievement). Congratulations!

(The third safe containing stash #12)

Now go back to Bourbon and finish the mission!

Q: How do you know the second building is actually a bank?
A: On the ground floor there is an abundance of ATM's, the third cache is located behind a heavy security gate and the room containing the safe is a vault covered in deposit boxes...

Q: Then why do you also call it an office building?
A: The sign on the building's facade reads 'sale' (ПРОДАЖА [...] 5-457-85). It seems to indicate that part of the building is being let or sold to others. Also the second floor has considerable desk space. While this can just as easy be still part of the bank, it is in any case clearly office space.

Q: Oh... so what about the barber shop?
A: The broken sign attached to the shop's front reads САЛО and IКМАХЕРСКАЯ. Elementary my dear reader, by using some extrapolation I was able to deduce that it must've read САЛОН ПАРИКМАХЕРСКАЯ, i.e. 'hair salon' or 'barber shop'.

Q: Wow. Okay. But the hotel was just a guess, right?
A: Nope.

For writing this guide I used the entry on the Ranger achievement at the Fandom wiki[metrovideogame.fandom.com] to find the location of the various stashes. I also copied, and modified, the description they gave of the locations.

All credits for stash locations and their description—wherever applicable—go towards the specific contributors of that wiki, a list of whom you can find here.[metrovideogame.fandom.com]