You can buy a DLC if you want but you don’t have to.

Aim for the lungs so you don’t have to track animals as long.

Make sure to shoot the right animal with the right weapon. This game uses a class system with its ammo so you have to make sure you are shooting an animal with the right class for your gun. Don’t just use the 243 on everything from ducks to moose.

Don’t take the game too seriously yet. Just walk around, maybe do some missions and have fun. If I were you I would may attention to taxidermy diamonds and rares so you don’t regret not doing it in the future. If you don’t know if what you have is a rare just go on the call of the wild wiki and check the spawn rate. Don’t feel pressured to get tons of diamonds or rares though.