When you complete the game the first time, you will unlock x-ray vision. Press (X) after you zoom in with the scope.
As you progress through the game, you will unlock better scopes.
Complete regions in career mode ynder any difficulty to unlock weapons and scopes:
Successfully complete the game under the easy difficulty setting to unlock Johanna, the sniper character.
Do not use the tree stand, tripod, or ground blind while crouched; you will die when you attempt to exit.
When in a tree stand and you want to get out, look down at the ground first. Then, get out.
The best place to hunt deer is Arizona. You need the buck decoy, buck call, scent cover, and the urine scent. First, use the decoy. Then, use the scent cover and urine scent. Finally, use the buck call. You should have bucks coming in a matter of seconds.
Go to the first Arizona level. Get on the four wheeler and go behind the cabin. At 200 yards there should be a deer.
Get a deer feeder and a tree stand. Walk to an area with a lot of trees. Set up your tree stand and deer feeder. Get up in the tree stand, use the scent cover, then use your buck call. It may take several minutes to attract a deer. For best results, use your rifles.