Hunting The Hunters - 15
Shoot 10 predators during a single player Arcade Shooting Gallery.
This is a simple achievement, in order to get this load up the first level on Montana (Woodlands) and as soon as you see a red sign in front of you look in to the distance on the right. Two mountain lions will run across the screen, shoot them and then don't shoot anything else. You will fail that section so will have to replay, rinse and repeat five times until you unlock the achievement. Also remember after each two kills to shoot the ground in order to lose your bonus or else you will get more points that required so will have to continue.
King of Reflexes - 30
Win any 1 Player Reflex Shooting Gallery hunting all animals in the correct order.
Switch to the 'Reflex Galleries' and enter the first available. All you have to do here is shoot the animals that the game tells you to and in the order that their symbols are shown. If you get the order wrong don't worry, let the timer run around and retry.
Deadeye - 30
Win any single player Shooting Gallery while not missing a shot and scoring 20000 or more.
Load up the first Montana gallery once more (first on the list) and take your time through each section. Once you reach the points you need to move on don't shoot anything else, this makes it simpler. Shoot what you have to and then stop until the next section. Also, don't make the shot if you don't think you can hit anything. If you don't waste all of your lives you should easily get over the 20,000 points mark.
Demolition Expert - 15
Shoot 10 exploding cans in single player Target Shooting Galleries.
Load up the first gallery in Reflex Mode and shoot the red cans which are dotted around. Replay twice and you should get it, there are 8 cans in total in this particular gallery.
True Hero - 15
In any 1 Player Arcade Shooting Gallery make your Hunter Award reach five stars.
This is rather hard if you have trouble aiming. Load up the first gallery in Montana and make sure you get as many of the deer at the beginning as possible without missing. Continue to shoot the animals without missing and you should get this achievement quite easily. It takes 25 kills without missing for this achievement to unlock as each star takes five kills to fill up.
Let Them Fall - 30
Shoot 100 birds in single player Shooting Galleries.
This will come naturally when you do the above achievements, it was one of the first that popped for me. Just shoot the birds when you see them.
Clean! - 30
Hunt at least 75% of male animals in any single player Arcade Shooting Gallery.
Load up the Woods in Montana (first in the galleries) and play through. You need to shoot 42 or more of the larger animals (larger than rabbits for example). If you get 42 or more kills (first total when you finish the gallery) the achievement should pop for you.
Story Mode Achievements:
Pimp My Gun - 90
Unlock and fully upgrade all the firearms.
As simple as it sounds really, just upgrade all of the weapons available. (Need help with the totals.
Pump It Up - 30
Hunt 300 birds with the Shotgun in Story.
Simply shoot 300 birds using the shotgun in the story mode, this may take you two playthroughs to get.
Hunting for Money - 90
Earn more than $50,000 in Story.
I got this around 3/4's through my first playthrough, just play as best as you can during each round and you should get this with little hassle.
Spoorer - 15
Find 20 tracks in Story.
Tracks are the yellow prints you will find using your detective mode, simple walk over them and press A in order to view the tracks. Do this 20 times and you will have your achievement.
Hungry for Fame - 30
Upload 20 pictures.
You can take pictures using your camera or every time you kill your trophy animal you get a special picture taken with it. You need to press X and login to Facebook using your details and then upload the picture, do this 20 times and you're done. This is glitched as I only need one more photo but the servers have seemingly stopped working. Works for some but others not.
Detective - 15
Spend 15 minutes total in detection mode.
You will be able to get this easily during the course of the story mode, but if you can't wait you can do it on the first level. As soon as you are taught how to use your detective mode simple stay in it until the achievement pops, just be careful your controller doesn't turn off midway!