Ever Vigilant is an achievement/trophy in Metro: Last Light that tasks the player with disarming 10 traps. They can be any kind of trap, as long as the symbol with wire cutters pops up - fuel containers or grenades on tripwires both count. All you need to do is cut the wire to disable it. This must be done on one playthrough. There are more than 10 traps in the game, but most are off the main pathway, so should be looked for carefully. The guide below lists them all.
In the level Facility, you will come to a section where you need to pull a switch to open a door to exit. Once you exit through the door you will drop down to the right into a brief tunnel section. It's between the point where you jump down and the ladder.
In the level Sundown, when you begin the level you will see a white box truck directly in front of you in a small yard. Go straight ahead and around the shed to the right to get to the rear of the truck.
From the truck you want to head to the other side of the yard ("west") and look for a shed with a car on its side semi-blocking the door.
"West" of the gas station is another row of buildings. Almost directly across from the gas pumps, which should be to your right, there is a trap blocking a hole that you can crouch and crawl through.
In the level Nightfall, when you get off the ferry, go straight to the building in front of you and go up the concrete ramp. In that main room is a trap very near where you enter.
From the same level of the building, turn around and make your way to the right side (looking from the ramp it's the left side of the building's upper floor) to find another trap before you get to a closed door.
You will eventually reach a building where you go up an escalator. At the top of the escalator, look to the right to find the trap connected from the top of the escalator to the left wall.
Immediately after and to the left of the last trap another one is blocking an open room.
Just to the right of the last trap and also connected to the escalator and the wall is this trap.
In the level Depot, as soon as the level begins you can travel all the way down the left side of the map to a broken wall which will lead to a large shed/garage. The trap is at the shed/garage door so do not run into the building.
In the level Dead city, the first one in Dead City is in the house to the right with the recording.
The second one is after you go down the hole with the slide if you turn around and go to the back of the room there is a room at the top of some stairs and a trap at the top of them.
The third is in the area before you climb up the ladder. In the leftmost side of the area (near back) there will be an opening around a corner. Go through and climb up some stairs at the end of the passage. Near the top next a doorway the trap will be in front of and diagonal to a table with a cassette player.