Here's a quick rundown of how to snag the Collectibles inside Gears of War 2. Enjoy!
Act 1 - Tip of the Spear - 13 collectibles
Chapter 1 - Welcome to Delta
1. Eagle Newspaper
Choose to train the rook. When you start the chapter, go straight until you come to a yellow van. Behind the van is a desk standing on its side. The collectible is a few feet from the desk.
2. Ambulance Driver's Log
Towards the end of the training, you'll slide down a ladder. After coming down the ladder, you'll see an entrance to a room that leads nowhere. Go in the room and you'll see a desk on your left. The collectible is next to the desk.
Chapter 2 - Desperation
3. Doctor's Journal - Dr. Nicolette Shannon
As you move through the hospital you'll see a blue sign that says "Wards 1 - 3" and an arrow pointing left. Go left and then go in the first room on your left. The collectible is on the floor in front of the bookcase.
4. Jacinto Medical Center File - Jonathan Harper
After going downstairs, you'll come to an open area with some Locust, one of which is in the middle of a horseshoe shaped desk. The collectible is in between the two halves of the desk.
5. COG Letterhead
After you leave the hospital you'll cross a courtyard and then enter a second building. Keep going through the building until you come to the kitchen. Across from the entrance to the kitchen you'll see a room with half of a blue double door. In the room is a desk. The collectible is in front of the desk.
6. COG Proclamation
After the last collectible, you'll come to a room with a flight of stairs leading down to an open area. Don't go down the stairs. Instead, go right upon entering the room, then go straight, then take a left down a dead end. See the ammo crate at the end? The collectible is next to it.
7. COG Tag - CSID: 085177-MJ3V5PB
Eventually you'll leave the building. When you do turn right and start looking for a pillar looking structure. The collectible is behind it.
Chapter 3 - Rolling Thunder
8. Grindlift Notice
Once you start the chapter, turn around 180 degrees and look to the left of the ladder to find the collectible.
9. Munitions Requisition Form
After you're back on the ground, turn to your left. See the two ammo crates? The collectible is left of the ammo crates.