this was my first achievement. i did the tutorial and the first basic hunt where you just need 1 deer, and also did the goal of hitting 5 rabbits for extra credits. after that i bought the recurve bow, and went to the Free Hunt in the fox run area. i started heading NW towards a bear icon on the map, and came across a fox. soon i noticed i was at a spawn point.
basically foxes just run back and forth forever. you can use your binoculars to make sure you are far enough back, also make sure to pack more arrows in your extra slots so you should have 30 shots. lay down, take aim, hold your breath, lead the fox a bit and let it fly. eventually you should hit one. hitting 5 also gets you another goal for more bonus credits.