One way to speed this achievement along is to go to Eletania in the Attican Beta cluster. There's a side quest there to find a missing data disk, and it has you checking several colonies of indigenous monkeys for the missing disk. All of these monkeys are killable and count as organic kills, for ~50 on the entire mission. They also count toward the weapon achievements (pistol, shotgun, etc) as well, serving as a good way to score numerous kills with unskilled weapons, since the monkeys don't fight back. You will get a few Renegade points on the first kill.