This guide is based on my own (and a few noted others') experiences in several playthroughs of the Bureau. The Combat Achievements are broken into two sections, due to restrictions on characters per section.

Update [10/03/2014]: I've added the R&D achievements. Thanks for the patience!
Update [02/19/2017]: Barring any additional content, I feel like this guide is complete. If something is grievously wrong, please let me know, but I'll no longer be answering posted questions.

These are the story-related achievements and will complete automatically as you progress through the game. In chronologicial order:

All That Remains
Escaped Groom Range


Bringing down Goliath
Defeat a Muton


Is He Old Enough to Drive?
Defeat a Sectopod


So Just Let Me Introduce Myself
Secured the package


The Devil's Tower
Infiltrated the Outsider Tower


A Dish Best Served Cold
Defeat a Titan


A Story of Axis and Allies
Closure


Exorcised the Demon
Retrieve and escape with information on the enemy base


...And the Body Dies
Confront the Outsider Leader


The Fat Lady Has Sung
Now, it's time to end this

The Last Suit You'll Ever Wear
Customize an agent


In the squad management area, you just need to change something about one of your agents.


Glad My Trust Wasn't Misplaced
Complete your first Dispatch Mission




Can't be Everywhere at Once
Complete 6 Dispatch Missions within a single campaign




Top. Men.
Get an agent of each class to Rank 5 within a single campaign.


I managed to complete this using Dispatch Operations before the squadmates I was using for my playthrough even popped level 5.


Away Team
Complete your first Minor Operation




See the World They Said...
Complete 6 Minor Operations within a single campaign




Spring Cleaning
Complete all Investigations in the base within a single campaign


Because the game saves progress towards an achievement, you will not be able to return to a missed earlier Investigation and complete it. The investigations, in order, are:

Radio Interference (available upon first base visit):
Ask Nico about the radio, then use the radio. Afterwards, talk to Chulski in the Radio room across the hall. Mention that you heard a strange signal, and ask her to set the Range to 250, Direction to North, and Frequency to 892.

Missing Silacoids (available after the second Major Operation and a Minor Operation):
After touring the lab with Weir, talk to Heinrich upstairs. Find the silacoids using Battle Focus to track their slime trails. The first is in the airlock as you leave the lab; the second is in the bathroom beneath Faulke's Office; the last set is upstairs in Ops in the room near Weaver's Office. Return to Heinrich and claim your Dispatch Mission.

Sleepwalkers (available after the third Major Operation):
In the hallway under Faulke's Office on the side of Operations to the left of the Map Console, find Heinrich, who will ask you to Battle Focus Scan several areas looking for infected persons. You'll need to scan every available area of the base, which will result in either a generic "No infected here..." or a glowing infected agent. After talking to the infected, return to Heinrich in the Lab and receive another Dispatch Mission.

Keeping Things Secure (available after third Major Operaiton):
Talk to Barnes in Engineering. He'll tell you that they caught a spy and are holding him in the next room. Talking to the Russian eventually yields a Dispatch Mission. I haven't found any combination of dialogue that doesn't result in a completion.

Vendetta (available after third Major Operation, after Weaver goes AWOL):
After talking to Faulke, and Weaver coincidentally disappearing, go downstairs and talk to Chulski in the Radio Room. She sends you to Percy in the Ready Room, who gives you more background on Weaver. Return to Weaver's Office in Operations and use the painting to find the safe. Use the combination on the other side of the office to open the safe and end the Investigation.

Test Flight (available after fourth Major Operation):
Talking to Barnes in Engineering reveals "microleaks" in the Avenger fueling system. Battle Focus Scan the three highlighted areas of the Avenger, and Barnes will ask you to shut off the leaky valves. Inside the Avenger, turn the top one. Down the ramp and to the left, shut off the first and third valves. If you mess up, Barnes will give you a generic "Wrong one..." message, and you just reopen the valve. Talk to Barnes again to complete the Investigation.

The Cure (available after fourth Major Operation):
Talk to Heinrich in the Laboratory. He sends you upstairs to Dr. Hara who, in turn, asks you to "wake up" a sleepwalker. Use "Time to Wake Up."; "We're about to win the war."; and "Come on, it's me, Carter." Talk to Heinrich again and claim yet another Dispatch Mission.

I've tried to put these in order by ease of completion. This is, of course, dependant on your style of play. If you're shooting for 100% completion, I would recommend playing on the easiest difficulty for all of these except Vigilo Confido, which requires Commander difficulty.


Dead Head
Get 20 Headshot kills with any gun within a single campaign


I managed to complete this before even leaving Groom Range on my first playthrough.


I've Seen Better, But Not Many
Reach Rank 5


This is will happen automatically, probably during your fifth or sixth operation.


Ready for Anything
Reach Rank 10


This didn't pop for me until about a quarter of the way through my final operation, so it might be missable if you don't play the minor operations.


Leader of Men
Give 150 commands to agents while in Battle Focus within a single campaign


This is probably an automatic achievement, even if you don't micromanage your team. By the time you finish a playthrough, you'll almost definitely have given enough commands.


Don't Run, You'll Just Die Tired
Attach 10 Sticky Grenades onto Outsider Enemies within a single campaign


While going for this achievement, I focused my grenade usage on the enemy snipers since they don't move often. Sticking the grenade to any enemy seems to work. You can get this easily by targetting the Sectoid in the Base's Shooting Range in the later portion of the game.


Welcome to Earth
Finish off 20 aliens using melee attacks within a single campaign


I got this by punching the silacoids that pop up during the non-major battles during Operations. Pretty simple with a Melee Pack. Can be done easily in conjunction with "Let the Boys Have Their Fun".


Sight Beyond Sight
Perform 15 unique scans within a single campaign


While planning your squad placement, enter scanner mode and move your cursor over the question marks. Scanning all enemies in range and all the weapons/ammo on the ground should give you this achievement by about mid-game.


Bursting the Bubble
Take down 20 Outsider Shields using laser-based guns within a single campaign


This will probably also pop automatically as you play through the game. I found the Laser SMG and the Laser Pulse Rifle to be the most effective for dropping enemy shields. To be clear, this only counts against the enemies like Shield Commanders who have a blue bar (shield) in addition to their health.


What Are You Without Your Armor?
Strip all of the armor off of 5 Mutons before killing them within a single campaign


I found the easiest way to get this achievement is to use grenades against the Mutons. This uniformly strips the armor off and you don't risk killing the Muton before all of his armor is gone.


Not Playing Favorites
Take an agent of every class into the field within a single campaign.


You can cheese this by finding a mid-Operation Supply Cache and switching your squad out. After you do this, you can switch back to your preferred agents.


We Will Fight Like Lions!
Defeat all the Outsiders before escaping on the Skyranger


I managed to miss this on my first playthrough. You're constrained by the bomb detonation, but if you grenade the Drop Pods when they first pop, have your Engineer lay down a turret for stragglers, you shouldn't have a problem here. Do a quick Battle Focus and survey the field before you leave to make sure you didn't leave anyone alive.


Clever Girl
Get 40 kills on Flanked enemies within a single campaign


See below for screenshots. You don't need to personally flank the enemies for them to count towards this achievement. When in Battle Focus, you can see the status of an enemy; usually you'll find them as being in Cover or Exposed, but some careful positioning of your agents will mark them as Flanked, and you'll get a massive damage bonus. Cover seems to work in 180 degrees, so the agent will need to be behind the object they're using for cover.

Pick an enemy behind cover. Multiple enemies can be flanked at a time, but this combat didn't easily allow for it.
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Move one of your guys into a flanking position; that is, move him so that he is not shooting from in front of the enemies' cover.

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When they're flanked, the game will tell you, and you'll get a massive bonus to damage.
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This effect can also be achieved with combat drones, which I don't use, so I can't display. The drone must be "thrown" behind the enemy cover while the enemy continues shooting at your squad. They will often move into an "exposed" position, instead of being tagged "flanked", but you can occasionally get kills this way, too.

It has been confirmed that you personally need to kill the enemies for them to count towards this achievement, but you do not need to personally flank them. Playing on Squaddie difficulty will also prevent your sqaudmates from stealing your kills if you choose to snipe squad-flanked enemies to get this achievement.

Let the Boys Have Their Fun
Complete an entire Operation without the player firing a weapon or using a grenade


Easier than it sounds. You can still use your abilities and melee enemies, just don't pull the trigger or lob a grenade. I would attempt this on a Minor Operation sometime after discovering Laser weaponry, again depending on your playstyle.

Grifter features a Muton as the toughest enemy, with a couple drones, outsiders and silacoids rounding out the rest. Code Breakers features a laser turret emplacement, several drones, and outsider snipers and elites.

They Won't Know What Hit Them
Use all of the agent and player abilities in the field within a single campaign


This one's a little daunting at first. As the Commander, you'll probably manage to use all of your personal abilities by the end of the game: Heal, Lift, Silacoid, Drone, Mind Control.

You'll need at least two Agents of each class as some of the abilities are mutually exclusive. The number beside the class below is the level at which the exclusive choice occurs. Some of these abilities can be used out of combat, utilizing the mid-Operation Supply Cache to switch out agents for abilities you don't normally use in combat.

Support [3]: Combat Stims, Shield Orb, Weaken, Disrupt
Recon [3]: Critical Strike, Cloak, Diversion, Fire Mission
Commando [4]: Taunt, Pulse Wave, Personal Shield, Plasma Field
Engineer [4]: Scatter, Mine, Rocket Turret, Laser Turret

You can get this achievement in the base by using needed abilities on the Sectoid in the Shooting Range.


Enemy Within
Have Mind Controlled enemies get a total of 15 kills within a single campaign


Mind Control is a player ability acquired at level 8. The game records progress towards an achievement as you progress through the game, so you can't get 8 Mind Control kills, reload from last checkpoint, get another 7 and have the achievement completed. The best way to ensure this achievement is to use Mind Control often and use it on the tough enemies (Muton Elites, Scouts, Minion Commander, etc.).


No One Left Behind
Complete the game without a single agent bleeding out


This is very simple at even Squaddie difficulty. Agents can begin to bleed out, but they must not finish (i.e. die). If one does, you can restart from the last checkpoint without any consequences.


Vigilo Confido
Beat the game on Commander difficulty without ever changing it


Self-explanatory. It'll probably take at least one Veteran playthrough before you're comfortable enough with the controls/AI to do this. I don't have a lot of recommendations for completing this, I would choose Medic (level 3), Lift Enhancement (level 5), and Support Drone (level 7), and roll with a Sniper and an Engineer for most of the missions.

This, and many other pre-DLC achievements, can be completed in the Hangar 6: R&D campaign. Some people consider this to be an easier route, as the DLC campaign is less challenging.

These are the story-related achievements and will complete automatically as you progress through the game. In chronologicial order:

Conduit Connection
Complete the first trial in Hangar 01


Drive Through
Trigger the Invasion in Hangar 6


It's In The Air
Defeat the Hangar 6 R&D Invaders



And, now, the ones you actually have to do stuff for:

Mind Blown
Destroy 60 enemies with DaSilva's Demo Charges within a single Hangar 6 R&D campaign


Use the Demo Charge ability that DaSilva starts with, and use it often. Because enemies tend to scatter when you get within the maximum range for this ability (while staying in cover), I wouldn't wait for them to cluster. Just use it as often as you can.


Know Your Groceries
Take a level 5 agent of every class into the field within a single Hangar 6 R&D campaign


Just like the original game counterpart: level at least one agent of each class up to level 5, then switch them out. Simple.


Conscientious Objector
Beat Hangar 6 R&D without firing any alien weapons


Again, pretty self-explanatory. Lowest difficulty selection will make this much easier. I'd recommend using the sniper rifle and assault rifle, but that's personal preference. You can use the microwave and lightning cannons as they become available. Be sure not to use Alien Sticky Grenades, as it will count against this achievement. Squadmates are allowed to use alien weaponry.


Only a Man
Complete DaSilva's perk tree without choosing Lift, Drone, or Mind Control


Yea... What it says.

Thanks for reading. And again, if you have any suggestions or requests for additional information, please leave a comment.

Special Thanks to:
Leo for testing and confirmation of "Clever Girl",
Mnesimache[www.trueachievements.com] of True Achievements[www.trueachievements.com] for confirmation of "Spring Cleaning";
Spartan2491[www.trueachievements.com] & Matwyn for confirmation and tips for "Don't Run, You'll Just Die Tired" and for tips on "They Won't Know What Hit Them";
Cooper for suggestions on "Let the Boys Have Their Fun".
Tynon_1221 for confirmation for "Conscientious Objector" from the DLC.