Cleaner - 10
Kill 10 pests
Dalek - 10
Kill 100 pests
At the beginning of a level the game will tell you which animal to hunt (i.e. rabbit x1) and show a second animal without a number besides it (not every level has pests). Those are pests and you can shoot them without penalty. The best level to grind the kills is the first level in Hossack. It has an open field and the pests can't hide. As soon as you kill a pest a new one spawns near it.
Trained up! - 20
Participate in all shooting range tests
There are three shooting ranges and the achievement unlocks as soon as you start the third one. The last two shooting ranges are available after getting the big game permit. Score doesn't matter. Unlike the hunting permits, you can't fail the shooting range tests!
Ninja! - 30
While stalking, do not get spotted by a big game animal
You can hunt big game animals after getting the big game permit. Follow the traces and make sure to stay in a safe distance. A bar in the middle of the screen will fill if you get spotted or the animal can hear you. Use the minimap to see in which direction the animal is looking.
Good student - 20
Get the hunting permit
This is the tutorial of the game and shows you the basic controls.
Hunting companion - 20
Get the dog-handler permit
This is the second class in the academy. Complete the tutorial and you'll unlock your dog companion and new levels.
No more joking around! - 20
Get the big game permit
The big game permit is the third class in the academy and will unlock new levels after completing the tutorial. Shoot the targets and get the necessary score.
Without breathing - 20
Get the pro permit
This is the last class in the academy and will unlock your last ability. Complete the tutorial to unlock this achievement.
Bull's eye - 20
Get the sniper permit
You'll have to shoot the targets and get the necessary score to complete this tutorial. Completing this academy class will unlock the sniper rifle which is one of the best weapons in this game.
Good reflexes! - 30
Kill a fleeing big game animal
Run into a big game animal and it will run away after noticing you. Shoot it and the achievement will unlock as soon as you kill it.
A hunter that knows how to hunt - 60
Unlock all of the hunter's skills
You have to reach Level 26 (100.000 Exp needed) to unlock the final upgrade. The best way to grind is the second last level in Marlborough ("A Land Where Game Is King"). It takes about a minute and gives you a minimum of 1.700-2.000 exp every round (more if you are good at aiming). The semi-auto shotgun is the best weapon because you can shoot three times before you have to reload.
The season's over - 100
Complete all of the hunt plans for the Hunting Season
You have to complete all six levels in all locations and the shooting range. Choose your cameo and weapon wisely to make it easier for you. Mountain cameo in most areas and forest cameo in the woods and a good shotgun. I used the sniper whenever it was available.
Bad master - 10
Having killed a dog
You unlock the dog after getting the dog-handler permit. Shoot your dog as soon as the level starts. This will fail the mission but you can restart without a penalty.
Poacher - 10
Kill a kangaroo
The first time I spotted a kangaroo was in the third Marlborough level. There's one near the start of the level. Don't worry if you miss it, the level is flooded with kangaroos. Several of the later levels got kangaroos too. You will fail the mission after killing the kangaroo and have to restart.
Bad hunter - 20
Kill an animal that is not in the hunt plan
Boars often appear as families with young boars and female boars. Shoot a young boar or female boar to unlock this achievment. This also works with deers and other animals that are not on the hunt plan. Shooting an animal that is not on the hunt plan will fail the level!