Section 1 - Fortress
After clearing the bunkers and before completing the section, you'll find a COG skull near the exit so go past it and enter the room with the Onyx ammo box. Beside it is the COG tag.
B. Michandani, PFC, Lake Station
Section 2 – Container Terminal
As you get past the gate, take out more enemy reinforcements. There's a COG tag in the barracks to the right. Just follow the trail of blood leading to a door to find the COG tag in front of it.
Section 3 – Motor Pool
As you move uphill, you should spot a COG tag skull ahead. Check the ledge above it to find the section's COG tag.
Section 4 – The Cliffs
Once the section starts, exit the tunnel and take the stairs to the left to find some bloodstains on the floor. The COG tag is located there.
Section 5 – Central Base
Shortly after starting the section, continue until the locusts ahead open fire on you from outside. Enter the room to the right and go downstairs. Immediately turn around and look at the floor beside the stairs to find a COG tag.
Section 6 – Central Control
B.Newman, PFC, Port Caval
As soon as the mission starts, go past the open hatch and go around the corridor to the right. At the end, you'll find a COG tag.
Section 7 - Beach
Once the section starts, follow your team to the breached door and look on the ground to your immediate left. You should see some bloodstains on the floor with a COG tag.