Half the achievements are easy to obtain in this game, while the rest are a bit time consuming. My advice would be to play through the game as a Recruit as a starter to gather the easy achievements. Ie. it makes it a lot easier to pick up Intels which are scattered throughout the missions. Then you can play with the Veteran difficulty level and collect the Veteran achievements, which basicly means completing missions and the whole game as a Veteran.
Note: the achievements can only be unlocked in single-player and with cheats off.
Make the Jump
20G
Infiltrate a cargo ship
Guide Complete the "Crew Expendable" on any difficulty level.
Earn a Winged Dagger
20G
Complete 'F.N.G.'
Guide Complete the training mission on any difficulty.
Win the War
40G
Complete the game on any difficulty
Guide Complete the game on any difficulty.
Dancing in the Dark
20G
Kill the power
Guide Complete the 'Blackout' mission on any difficulty.
Save the Bacon
20G
Protect 'War Pig', the Abrams tank
Guide Complete the 'War Pig' mission on any difficulty.
Death From Above
20G
Operate an AC-130 gun ship
Guide Complete the 'Death from Above' mission on any difficulty.
Wrong Number
20G
Find Al-Asad's safehouse
Guide Complete the 'Safehouse' mission on any difficulty.
Piggyback Ride
20G
Carry Cpt. MacMillian to safety
Guide Complete the 'One Shot, One Kill' mission on any difficulty.
Desperate Measures
20G
Corner Zakhaev's Son
Guide Complete the 'The Sins of the Father' on any difficulty.
Look Sharp
20G
Find 15 enemy intel items
Guide See 'Eyes and Ears'.
Eyes and Ears
20G
Find 30 enemy intel items
Guide Collect all Intel laptops scattered around the missions. Here is a list where you can find them all (video by MetalCard):
Down Boy Down
20G
Survive a dog attack
Guide This achievement can only be unlocked if the dog jumps you. Shooting it will not work.
Just wait for the dog to jump you and wait for a button icon to appear on the screen, then immediatly press the button to snap the dog's neck. In my case it was the right stick button. Other sources says that in some cases it might be the 'A' button.
New Squadron Record
20G
Complete the cargo ship mockup in less than 20 seconds
Guide This is an annoying achievement. This is during the training missions (F.N.G.) when you are running the training course. Remember that accuracy is very important, so don't empty your clips on a single target. Aim and fire a single shot at each target. Also sprint instead of running when possible. This will save you some time.
When you first swing down from the ramp use your MP5 on the first 3 targets, run down the stairs and shoot the 4th target. Throw the flash grenade in to the room your told to throw it in to, then quickly switch to your handgun before the flash grenade explode. From now on use your handgun on the remaining targets. It's easier to use for accuracy.
If you fail the first attempt, just climb the ramp and give it another try. Remember to pick up a new set of flash grenades and importantly: reload your weapons!
Rescue Roycewicz
20G
Save Pvt. Roycewicz on the stairs
Guide In the beginning of "The Bog" mission you will infiltrate a building right in front of you. Quickly run in to the building, switch to night vision and look to your right. There should be a set of stairs. Pvt. Roycewicz will be standing at the bottom of the stairs, then he will run up. Quickly follow him and you will see him be jumped by a single soldier. Simply kill the soldier.
Your Show Sucks
20G
Destroy all the TVs showing Al-Asad's speech
Guide Simply destroy all TV's broadcasting Al-Asad on the 'Charlie Don't Surf' mission. Here is a list where you can find them all:
Important to know: if you destroy a TV and get killed before you reach another checkpoint, you have to destroy the TV again.
Man of the People
10G
Save the farmer
Guide During the 'Hunted' mission you will encounter 3 enemy soldiers harassing a farmer. Wait for the order, then take out the soldiers. Do NOT fire until you get the order!
Straight Flush
20G
Kill 5 enemies with one shot while in the AC-130 gunship
Guide During the "Death from Above" mission, use the 105mm gun on large crowds of people. You will unlock this achievement quickly.
Ghillies In The Mist
20G
Complete 'All Ghillied Up' without alerting any enemies
Guide You are now a sniper, so carefully take down enemies without alerting others. The first two enemies you encounter you simply take down one and let Capt. Macmillian take the other one. You will then reach a house. Do not engage. Wait for Macmillian's order to move on. When you reach a church, take out the guard in the tower, then take down the one on the ground. You will then reach a large open area. This area will soon be patrolled by a large number of enemy soldiers. Do not jump the fence in front of you yet! Move to the right part of the fence (not to far, you don't want to lie in the radiation area), then lie down under the fence. This way none of the enemies will spot or step on you. The next set of enemies (the ones unloading dead bodies) you can simply ignore. Sneak around them following Macmilliam, however beware of two soldiers patrolling the surrounding area. The next obstacle is when you and Macmilliam run into an open area filled with soldiers. Simply stay right behind him, and for God's sake, sprint! Don't run. From now on the rest is piece of cake!
If you are spotted you will most likely be killed. Don't know if respawning will work, so i restarted the mission to be sure the mission is reset.
Mile High Club
20G
Sky dive to safety on Veteran difficulty
Guide Complete the epilogue on Veteran difficulty. The hardest achievement in this game. My advice here is to use your flash grenades wisely. Stun your enemies and move forward while picking them down one by one. Never stop to regen your health. There is no time for that. Use this video for guidance:
No Rest for the Weary
10G
Stab an injured crawling enemy
Guide Quite an easy one. You will encounter many wounded enemies lying on the ground during the game. Simply walk up to one and finish him off with your knife.
Deep and Hard
90G
Complete the game on Hardened or Veteran difficulty
Guide Not the hardest game to complete on the hardest difficulty. If you've played any of the other CoD games on Veteran, you probably already know the drill how to complete it this time.
If not, remember these steps: - Never run around corners - When possible, let your comrades run infront. They will clear most of your paths - Stay low and use cover all the time. Sprinting is generally a bad idea - If you get stuck at any point, use the forum and ask for guidance. Or search Youtube for strategy movies. Good luck!
The Package
40G
Complete 'Crew Expendable' on Veteran difficulty
Guide See 'Deep and Hard'.
The Rescue
40G
Complete 'Blackout' on Veteran difficulty
Guide See 'Deep and Hard'.
The Search
40G
Complete 'Charlie Don't Surf' on Veteran difficulty
Guide See 'Deep and Hard'.
The Bog
40G
Complete 'The Bog' and 'War Pig' on Veteran difficulty
Guide See 'Deep and Hard'.
The Escape
40G
Complete 'Hunted' and 'Death From Above' on Veteran difficulty
Guide See 'Deep and Hard'.
The First Horseman
40G
Complete 'Shock and Awe' on Veteran difficulty
Guide See 'Deep and Hard'.
The Second Horseman
40G
Complete 'Safehouse' on Veteran difficulty
Guide See 'Deep and Hard'.
The Shot
40G
Complete 'All Ghillied Up' and 'One Shot, One Kill' on Veteran difficulty
Guide See 'Deep and Hard'.
The Third Horseman
40G
Complete 'Heat' and 'The Sins of the Father' on Veteran difficulty
Guide See 'Deep and Hard'.
The Ultimatum
40G
Complete 'Ultimatum', 'All In', and 'No Fighting in the War Room' on Veteran difficulty
Guide See 'Deep and Hard'.
The Fourth Horseman
40G
Complete 'Game Over' on Veteran difficulty
Guide See 'Deep and Hard'.
Daredevil
10G
Kill an enemy while blinded by a flashbang in the single player campaign
Guide This means that you have to be blinded, not the enemy. Simply throw a flash grenade at someone, get yourself blinded and kill the enemy before your sight is fully recovered.
Roadkill
10G
Kill 2 enemies by blowing up a car in the single player campaign
Guide Can be done on the "Death from Above" mission. There should be enough cars around to try your luck at. Wait until at least two enemies are standing by a car and blow it up with the 40mm gun.
Bird on the Ground
20G
Shoot down an enemy helicopter with an RPG in the single player campaign
Guide This can be done on the 'War Pig' mission. Once your mission start make your way straight ahead to the bus wreck. There should be some RPG's behind it. Wait for the two helicopters to appear and blast one down.
Four of a Kind
20G
Kill 4 enemies in a row with headshots in the single player campaign
Guide I unknowingly unlocked this one during the 'War Pig' mission. The enemies will rush in quickly so all you have to do is pick them out with your sniper rifle.
Three of a Kind
10G
Kill 3 enemies in a row with your knife in the single player campaign
Guide This can be unlocked anytime during the game while playing on Recruit difficulty. Since you can take a great amount of health damage, it shouldn't be a problem to run up to 3 close standing enemies and stab them.
Hard achievements 
