The game has total of 33 collectibles in 5 Acts. All collectibles are immediately saved if you pick up them. In the main menu under the point COG tags / comics you can see how many collectibles you have in a act, each comic is one act. None of the COG tags are missable, you can replay every time you want a chapter. For this achievement you need 22 / 33, if you follow my guide you will unlock the 22th COG tag in ACT 3 - Darkest Before Dawn.
I have one video for all 33 collectibles. The video shows in progress of the mainstory the collectibles, you see also the current missionobjective, the act and the COG Tag count in the left upper corner of the video.Act 1 Ashes
Act 2 Nighfall
Act 3 Belly of the Beast
Act 4 The long road home
Act 5 Desperation