Estimated time for 1000: 15+ hours.
Minimum playthroughs: 1 (2 recommended)
Missable achievements: Eyes and Ears: if you accidentally pick up any intel while cheats are active you can no longer unlock this achievement until you remove your save file from your system's memory.
Glitched achievements: None
Offline: 37 (1000)
Online: 0 (0)
Cheats disable achievements: Yes
Most of the achievements are pretty easy to pick up in just one playthrough if you know what to do. You could do everything in one playthrough on veteran but since veteran is very difficult it's best to start on normal or easy and grab all the miscellaneous achievements while preparing yourself for veteran. As far as veteran goes, it's hard. Most of your time in the single player will be spent getting killed in veteran unless you're a god at Call of Duty.
Step 1: Start a new story on easy mode. Since you're pretty much invulnerable to enemy fire on easy we're going to focus on grabbing most of the miscellaneous achievements as well as all the intel along the way.
Step 1.0: As a reminder, be sure to grab all the intel along the way; Any you miss can be grabbed during subsequent playthroughs but if you're on easy now it's just going to be more difficult.
Step 1.1: During the first actual level 'Crew Expendable' you'll come to a drunken man near the very start of the level. Aim at him and throw a flash, once you're blinded unload your gun in his general direction and you should get the achievement "Daredevil." If your team killed him before you could you can go into the nearby room and simply aim at the sleeping enemies, throw a flash, and then kill them while blinded for credit.
Step 1.2: While we're going through the story mode we'll have to get the achievements "No Rest for the Weary", "Roadkill", "Four of a Kind", and "Three of a Kind." We may as well do them on 'Blackout' but they can be done anytime you feel comfortable doing them.
Step 1.3: Throughout the level 'Charlie Don't Surf' there are going to be a bunch of TV's around that you'll have to destroy. Destroy all of them and you'll unlock the achievement "Your Show Sucks." Most of them are in one room near the end but here's a YouTube video for more help.
Step 1.4: While going through the level 'The Bog' you'll head up a flight of stairs and see one of your buddies being attacked. Kill the assailant before he kills your friend and you'll unlock the achievement "Rescue Roycewicz."
Step 1.5: During the level 'Hunted' you'll eventually come to the point where you'll be watching a farmer talking to some enemies. Once Price gives the order kill the enemies and you'll unlock the achievement "Man of the People."
Step 1.6: During the level 'Death From Above' try to find a group of five people near each other and then hit them with the 105mm gun to kill them all and get the achievement "Straight Flush." Look around for a car to shoot and check if at least two people are near it. If there are destroy it with the 25mm and you should unlock the achievement "Roadkill."
Step 1.7: At the start of the mission 'Warpig' run forward and grab the RPG near the empty bus. A helicopter will be arriving shortly to drop off enemy troops. Take out the RPG and shoot the helicopter when you've got a good shot. Once it goes down you should unlock the achievement the achievement "Bird on the Ground."
Step 1.8: During the mission 'All Ghillied Up' you'll have to stay completely unnoticed during the level. There will be times when you'll be given the choice of killing people of sneaking around. Pick the option to sneak around throughout the level and you'll unlock the achievement "Ghillies In The Mist."
Step 1.9: While you're going through the game you'll fight dogs at a few different times. If they happen to jump on you you'll be shown a button prompt and then upon hitting it will snap their neck. I found dogs the easiest to fight against on the level 'One Shot, One Kill.' While following McMillian you'll go through an old building. A few dogs will pop out of a door and attack you. Later in the level a lone dog will be eating something. Even later there will be a swimming pool full of dogs. Allow any to jump on you and then hit the button prompt and you'll unlock the achievement "Down Boy Down."
Step 2: Now with your new found leet Call of Duty skills start a new game on veteran. During the first level 'F.N.G' you'll be asked to do a training course. If manage to finish in under 20 seconds you'll unlock the achievement "New Squadron Record."
Step 2.1: Now you'll have to actually beat the game on veteran. Each level will give you an achievement and finishing every level will give you another worth 90. Go slow, use cover, allow your team to help, use grenades when necessary, and try to remember the levels from your previous playthrough(s.)
Step 2.2: During your veteran playthrough you may as well grab any intel you're missing as well as any miscellaneous achievements you didn't get.
Step 3: After finishing the game on any difficulty you'll unlock a new level to play from the mission select screen. Under epilogue you'll be able to play the mission 'Mile High Club' which is certainly one of the harder achievements in the game. It'll take quite a few tries but check out a few YouTube videos, read a couple of guides, and you should be able to down this in less than an hour of trying.