Assassin's Creed Chronicles: Russia

There are two ways to deliver headshots in AC Chronicles: Russia. One is to use Nikolai's rifle subweapon and aim headshots at guards. The other is to play through the scattered sniping sections throughout the game. I recommend doing the latter, as you won't have to worry about running out of ammo, and enemies appear more frequently.

It's quite possible that you will unlock this trophy naturally during the course of your two playthroughs, but if you want to farm this early on, play through the first sniping section of Sequence 7 until the point when Anastasia runs into the house, where enemies will become harder to kill because of the presence of walls and windows. Headshot all eight enemies outside, then reload the checkpoint. Repeat until you unlock the trophy.