Carnivores: Dinosaur Hunter HD

You should always be aiming to achieve one-shot kills when you're hunting, these are made particularly easy when using the Sniper Rifle in conjunction with "X-Ray Visor" (that being said they're still entirely possible with other guns on most dinosaurs). When aiming at dinosaurs with X-Ray Visor enabled all vulnerable areas are highlighted; you want to be aiming for the heart which is naturally highlighted red. A clean shot to the heart from a moderate/close distance does the trick more often than not, and it's practically inconceivable that you won't achieve well in excess of 25 one-shot kills on your way to the game's other trophies.