Before we begin, it is important to emphasize the amount of time it will take you to achieve all these achievements. Personally it took me around 50 hours but with this guide you can probably do it in 30.
Some achievements require another player to grind them more easily like the online ones and are probably the worst of all.
There are quite a few achievements that require matches in local lobbies to farm kills on the different vehicles, keep that in mind.

Recruitment Drive: Complete Navigation Training.
This one must be a breeze, just complete the first training level and get any medal.


Training Day: Complete all the Basic Training levels.
Complete those easy levels from the training field, from navigation to sheep training.


Passing Out Parade: Complete all Training levels.
There's also pro training levels so keep completing them.


Specialist Forces Qualified: Gain a Gold Medal on all Training levels.
This is kinda hard since there are pretty difficult levels like the sheep rope or ninja rope ones with tight time limits, so here's a video guide of how to complete them in the most efficient way by Trophy Boiii.

Halfway house: Complete 15 Campaign Missions.
Keep completing missions until the achievement pops up, not that hard.


Sub Standard: Complete 40 Sub Goals.
Each mission has 3 secondary tasks, you can do them in a single run or complete one at a time, just take your time and you'll get it.


That Camp was no Pain: Complete the Campaign.
The first missions are a breeze but the lasts ones are hard as hell.


Billy No Mates: Complete all the Sub Goals.
Perhaps you've completed the game but it is time to complete the secondary tasks in order to get this achievement, here's a full playthrough by Pete the Sheet of hot complete every mission with every task in one go, credits to Pete.

Challenge Accepted: Collect a wanted poster.
There will be 10 wanted posters across the campaign, they´re always inside buildings, grab one of them and the achievement is yours.


Call that a Challenge!: Complete 5 Challenges.
After grabbing the posters you must unlock the challenges attached to them, clear five of em and the achievement is yours.


No Challenge at all: Complete all Challenges.
Here's a detailed video about the location of every single poster and their challenges by Mindless Walkthroughs, perhaps is obvious but the video isn't mine lol, credits to the guy.

I'm Your Father!: Win an online multiplayer match in Sudden Death.
Just create a local game and change the settings so that sudden death is instant and finish the game by choosing one worm per team.
If that doesn't work, try setting the sudden death counter to 5 minutes.


Unstoppable: Win 3 online games in a row.
Probably you'll get it while doing the "Bleating ranker" achievement.


I built this city: Win an Online game with all worms in Buildings.
Can be done with a friend on a ranked or normal online game, just put your worms on a building and ask your friend to lose the match.


Bottom Rung: Play a Ranked Match.
Just go to the multiplayer menu and search a 1v1 ranked match, after losing or winning the achievement is yours.


Online Warrior: Play 50 Online Multiplayer Games.
Probably done after reaching the sheep rank for the next achievement if it isn't just keep searching matches or create them and play them with some friend, do them fast by setting the worms at 1 per team.


Bleating Ranker: Reach Sheep Rank.
This is the tricky one, you need to be exceptionally good at the game or have a friend who is willing to help you.
In case of having someone, they will have to search for a game at the same time to be matched, one will be allowed to win until the other player reaches the sheep rank, in total there are 6 experience bars that must be filled, each one asking for approximately 100 points of exp.
If you have a high-ranked partner it will be faster since the exp is proportional to the opponent's rank.
It should be noted that players cannot drop in rank after reaching a new one, which will make all farming more efficient.
There will be times when the game will pair you up with other people, it is always best to exit the game as it is very unlikely that they will let you win.
If you manage to reach a 3 win streak you will get extra experience points.
The most efficient way to finish the games is to make your friend appear his worms in the water.
(Takes about an hour if your opponent is high ranked or probably four hours if they are low ranked.)

The Worm that Turned: Kill 4 worms in a single turn.
Can be done in some levels of the campaign but the easiest way to do it is in a local match by setting a team of 4 worms with 1 hp each, explode them, drown them, do whatever it takes to kill them in one turn and the achievement is yours.


Grave Digger: Kill 500 worms.
This must be cleared at the end of the campaign or after doing the next achievements, if not, keep killing worms on local matched with your worm team.


Mount Killmore: Get 40 kills using a Mounted Gun.
This is where it gets grindy, you can do it by playing normaly but the fastest way is by creating a local match with 5 extra teams controlled by you, set the worm number to max and hp at 1 and activate the teleport option (so you can spawn all worms in a single location near a mounted gun)
Remember to increase the amount of mounted guns on the match settings, kill the rest of the worms with your main worm and you'll get the achievement.


Roto Boating: Get 80 kills in a Helicopter.
Same as the last achievement just replace the mounted guns with the chopper, remember to increase the amount of vehicles and you should be fine with 2 matches.


Tanks a lot buddy: Get 80 kills in a Tank.
Same as the previous achievement, just replace the chopper for a tank.


Mech me Proud: Get 80 kills in a Mech.
Same as the previous achievement, just replace the tank for a mech.


You're so Pushy: Kill 20 worms with Prod.
Same as the previous achievements, just replace the vehicles with a prod near a fall or water.

Gym Membership: Finish a game with a worm on more health than it started with.
Self explanatory, you'll probably get it on a story mission.


You Crafty Devil: Craft 30 weapons across all game modes.
Can be easily achievable with the "Do it yourself" achievement.


Full of Swag: Fully customise a team of Worms using unlocked customizations.
As you'll progress through the campaign or challenges you'll be awarded with customization item, just modify your worms with them and you should be fine.


Sweat Shop: Unlock all the Customization Items.
This one sucks, in order to get this achievement you must reach lvl 30 and complete every challenge, the grindy part is the lvl 30 one as the exp required is absurd at the final levels, if you finish the campaign you'll be propably at lvl 25 or so, farm exp for ranked matched as you try to get the "Bleating Ranker" achievement since those matches award you a lot of exp too.


Do It Yourself!: Craft every weapon in the game.
This one will take you like 15 mins or so, there's a campaign mission called "Créme de la Kremlin", that's the mission that teaches you the crafting system, just grab the boxes and craft every item (including the base weapons and the jump rope) reset the mission if you run out of resources.

That's all, you've (probably) mastered the game and those achievements will be yours soon enough, remember to keep your calm since these achievements are kinda tiring to do.
Let me know if this guide was useful, if it was consider to add this guide to favourites :D
So... HAPPY HUNTING GAMERS.