Originally Posted by iBuzz7S
Excluding the collectible stuff (Templar and Flag bullshit) I completed all other tasks before assassinating anyone. That's how I got my achievement.
Pretty sure that's how it is supposed to be done.
Yep that's how I did it too. I saved the templars and the flags for later. Once I did all the investigations, save citizens, etc I did the assassination and was able to get the achievement.