This is a 100% achievement guide for battlefield 3.
All achievements are multiplayer only and usually open/unlock after you closed the game and restarted it on the next go.

M.I.A
Took your first enemy Dog Tag

To get enemy Dog Tag you have to kill them with a knife. Sneak up behind them or rush behind them and just kill them with a knife.

It's better than nothing!
3rd MVP in a ranked match

To get this achievement, you have to finish 3rd overall in the match.

1st Loser
2nd MVP in a ranked match

To get this achievement, you have to finish 2nd overall in the match.

Most Valuable Player
MVP in a ranked match

To get this achievement, you have to finish 1st overall in the match.

Infantry Efficiency
Received all 4 weapon efficiency ribbons

To get this achievement, you need to get four ribbons atleast once each. You do not need to earn all ribbons in one round for this achievement to unlock.

-Assault Rifle Ribbon (Get 7 kills with Assault rifles in one round)

- Sniper Rifle Ribbon (Get 7 kills with Sniper Rifle in one round)

- Light Machine gun Ribbon (Get 7 kills with Light Machine guns in one round)

-Carbine Ribbon (Get 7 kills with Carbines in one round)

You can die between the 7 kills.

Man of Calibre
Completed a round of Gun Master

To unlock just complete a round of Gun master (do not need to win).

Support Efficiency
Received all 4 support efficiency ribbons

To get this achievement, you need to get four ribbons atleast once each. You do not need to earn all ribbons in one round for this achievement to unlock.

-Medical Efficiency Ribbon (Get 5 revives in 1 round)

- Maintenance Efficiency Ribbon (Repair 7 times in 1 round)

- Resupply Efficiency Ribbon Ribbon (Get 7 Resupplies in one round)

-Surveillance Efficiency Ribbon (Get 5 motion sensor assists in one round)

Dominator
Won a round in Conquest Domination

Self Explanatory: Win a round of Domination

Deadly tools
Without dying, got a kill with a Carbine, Pistol and Rocket Launcher

To start of: You need to kill with a carbine (any assault rifle with engineer class, Scar-H, M4A1 and so on) a rocket launcher (Smaw/rpg) and a pistol.

Colonel
Rank 45 achieved!

Self Explanatory: Get rank 45 (Battlelog you see your level)

Death from above
Got one kill with the Gunship

Specific maps spawn Gunships, all you need to do is kill someone with a gunship.

Dropship
Destroyed the Gunship

Self Explanatory: Use any weapon (Anti Air, Jet, Heli) to shoot down a gunship.

Jaws
Took a swim in the Oman Hotel swimming pool

Nothing to add, just swim at Oman Hotel.

Vehicle Warfare
Received all 3 vehicle warfare ribbons

-Air Warfare: Kill 5 enemies in a single round with any of these: Jets, Helicopters

-Transport Warefare Ribbon: Kill 4 enemies in a single round with any of the transport Vechicles (Humvee, Vodnik, Growler, Buggy etc..)

-Armoured Warfare Ribbon: Kill 7 enemies with LAV or Tanks.

Capture The Flag
Captured one flag while playing CTF

To Unlock Capture a flag.

Grinding the Crack
Fell over the edge on Ziba Tower

To unlock jump down Ziba Tower.

Extreme Hoarder
Picked up 50 weapons in Scavenger mode

Nothing to add.

Heavy Lifter
Killed an enemy after successfully paradropping a vehicle

To unlock: You have to get a gunship and then you will get the Option to choose "Dropship IFV" which will then drop you from the ship while inside the IFV. Now when you land you need to get atleast 1 kill using it.

AAs revenge
Destroyed an air vehicle using the AA jeeps

Nothing to add.

Bite your finger
Found the secret reptile

To get this achievement, start a new round of conquest on Epicenter.
Head to "C" and crawl directly easy from it to the pipe.
There is a dinosaur statue inside.

Superiority
won one round of Tank Superiority

Nothing to add.

Its no sidecar
Got a kill from the passenger position on a motorcycle

Just kill someone as a passanger.

Offroad
Got one kill with the Quad bike

Nothing to add

Third Tour
Got a kill with each of the following vehicles: the BTR-90, DPV and F-35.

Nothing to add

Handyman
Unlocked all xbow parts

To Unlock: You need all parts
Assignments:
-Win 3 round of scavenger - Unlocks Crossbow

-Get 20 spot assists - All you need to do is aim at a target and press select for them to be spotted and then let someone kill them or place down TUG-s.
-Designated 10 Vechicles - You need to laser 10 vechicles using the SOFLAM.
-Get 1 designated assists - From the above point your teammate has to kill one.

Those 3 will unlock - Scan Bolt

-Get 50 kills with Sniper - Should come naturally
-Get 10 headshots using sidearm - secondary weapon

Those 2 will unlock - BA Bolt

-Get 5 kills with hand granade
-Get 5 kills with underslung genade - Granade launchers basically known as M 320 attachments.
-Get 5 kills with C4

Those 3 will unlock HE Bolt

-Total of 150m Headshot with Sniper Rifle
-Total of 150 headshot with Assault Rifle
-Total of 150m headshot with Carbines

All thoes above are fairly easy to do as its total combined.

Those 3 will unlcok - Crossbow Rifle scope.

Pocket full of death
Without dying, got a kill with xbow, primary weapon, and hand grenade

Nothing to add

Show of Force
Got 10 kills with all ten CQ weapons

To unlock get 10 kills with each of the new weapons on this DLC. Picking them up from dead bodies count

Weapons Required:
Assault: AUG A3, SCAR-L
Engineer: ACW-R, MTAR-21
Support: L86A2, LSAT
Recon: M417, JNG-90
All Class: SPAS-12, M5K

Assignments Assault:
-AUG A3:
10 Squad Revives
30 Assault Rifle kills

-Scar-L
20 kills with granade launcher
15 kills with hand granade

Assignments Engineer:
-L86A2
20 Squad resupplies
20 kills with LMG

-LSAT
10 kills with C4
10 knife takedowns

Assignments Support:
-ACW-R
20 AT rocket kills (Javelin kills count)
30 kills with carbines

-MTAR-21
Get a kill with EOD bot
100 kills with carbines

Assignments Recon:
-M417
10 T-UGS assists
Capture 20 flags

-JNG-90
50 kills with sniper rifle
win 3 rounds of conquest domination

Assignments All class:
-SPAS-12:
20 kills with pistols
20 kills with shotgun

-M5K
Finish top 5 in gun master
100 kills with sub machine guns.

Home made javelin
Destroyed an enemy vehicle using the xbow

Nothing to add

Like a Boss
Got a kill with the skid loader

Skid Loader is on Wake island, run someone over with it.

Transport Pilot
Transported a flag carrier in an air vehicle in CTF

Nothing to add

Decorated
Received one of each ribbon in the game

You have to get the following:
-Assault Rifle Ribbon - Kill 7 in a round with Assault Rifle
-LMG Ribbon - Kill 7 in a round with LMG
-Carbine Ribbon - Kill 7 in a round with carbine
-HandGun Ribbon - kill 4 in a round with pistol
-Sniper Rifle Ribbon - kill 7 in a round with sniper
-PDW ribbon - kill 7 with personal defense weapons (P90, PDW-R, PP-2000, UMP-45)
-Shotgun Ribbon - Kill 7 in a round with shotgun
-Disable Vechicle Ribbon - Disable 4 vecicles in a round (Before you destroy it you disable)
-AntiVechicle Ribbon - Destroy 3 vechicles
-Melee Ribbon - Kill 4 with a knife in 1 round.
-Surveillance Ribbon - Get 5 motion sensor assists in a round
-Medical Efficiency Ribbon - Revive 5 in a round
-MVP Ribbon - Be the best player in lobby
-MVP 2 Ribbon - Be the second best in lobby
-MVP 3 ribbon - Be third best in lobby
-Supression Ribbon- Get 4 supression assists in a round: Easiest way to do this is to have someone that you play with
-Avenger Ribbon - In a round get 2 avenger kills
-Saviour Ribbon - In a round get 2 saviour kills, kill someone that is shooting your teammate.
-Accuracy Ribbon - In a round get 5 headshots
-Ace Squad Ribbon - Be part of the best squad
-Flag Defender Ribbon - In a round get 5 Flag defend kills
-Flag attack ribbon - In a round get 4 flag captures (Has to be done in conquest, you have to be the first one to the spot)
-Resupply Efficency Ribbon - In a round get 7 resupplies
-Maintenance Efficiency Ribbon - In a round get 7 repairs
-M-Comm Defender Ribbon - In a round defend 2 M-Comm stations (Has to be done in Rush, you have to kill someone who is planting.)
-Nemesis Ribbon - In a round get 2 nemesis kills (Kill 1 player 5 times to become nemesis)
-Stationary Emplacement Ribbon - Kill 2 enemies with a mounted gun.
-Squad Wipe Ribbon - In a round get 2 squad wipe bonus (you need to eleminate a squad, it does not have to be the same squad and dosent matter how many people are in a squad).
-Air Warfare Ribbon - In a round kill 5 enemies with air vechicle
-Transport Warfare Ribbon - in a round kill 4 enemies with transport vechicle
-Armored Warfare ribbon - in a round kill 7 enemies with a land vechicle.
-Anti-Explosive Ribbon - In a round destroy 3 enemy explosives.
-Squad Spawn ribbon - In a round get 7 squad spawn bonuses.
-Combat Efficency Ribbon - In a round get 3 streak bonuses (you need to get 8 kills without dying to net one of these)
-Rush Ribbon - Finish a game of Rush
-Rush Winner Ribbon - Win a game of Rush
-Conquest Ribbon - Finish a game of conquest
-Conquest Winner Ribbon - Win a game of conquest
-TDM Ribbon - Finish a game of TDM
-TDM winner Ribbon - Win a game of TDM
-Squad Rish Ribbon - Finish a SQD rush game
-Squad Rush Winner Ribbon - Win a SQD rush game
-Squad TDM Ribbon - Finish a game of SQD TDM
-Squad TDM Winner Ribbon - Win a game of SQD TDM

Gunslinger
Got 10 kills with each of the ten Back to Karkand weapons

Assault:
-FAMAS
10 revives
10 heals

-L85A2 (Unlock FAMAS to enable)
100 assault rifle kills
20 kills with granade launcher
Win 5 matches of Squad Deathmatch

Engineer:
-G52
10 Repairs
1 Infantry Repair Torch kill

QBZ-95B(Unlock G53 to enable)
50 AT RPG Kills
1 Enemy Vechicle Destroyed with Repair tool
5 conquest wins

Support:
-QBB-95
20 LMG kills
2 Mortar Kills

-MG36 (Unlock QBB-95 to enable)
100 LMG kills
50 Suppresion assists
50 resupplies

Recon:
-QBU-88
20 Sniper Rifle kills
5 laser designations

-L96(Unlock QBU-88 to enable)
50 HEadshots
50 spot assists
5 knifes

General:
-PP-19
Arm 10 M-coms(Rush)
10 Flag Captures(Conquest)
2 hours played on strike at Karkand

-MK3A1(Unlock PP-19 to enable)
10 kills with PP-19
5 kills in DPV Jeep
10 kills in BTR-90
2 hours played on Sharqi Peninsula
2 hours played on Gulf of Oman

Destroyer
Got 10 kills each with Tank destroyers and Mobile Artilleries

To Unlock you need to have 10 kills with any of the Tank Destroyers (SPRUT-SD and M1128) and 10 kills with Mobile Artillery (BM-23 and M142)

Complete Warrior
Got a kill with the following weapons in a single life: Assault Rifle, Jet, Tank

Nothing to add