Creature of Habit, Devotchka, Big Money, Aid and Comfort, There Are No Dominos - These unmissable achievements are unlocked as you progress through the story missions of Stones Unturned.
Did I Forget Something? Skip Trace - These achievements are unmissable if you complete the Bounty Hunting quest line.
Big Fat Party Animal - Kill 50 enemies using the Hartmann 7.62mm machinegun while wearing the Party Animal shirt. This can be a bit of pain in the endgame because there a re so few enemies left. Best bet is the endless underboss missions. Of those, The Righteously Fucked is probably the quickest way to get the requisite kills under your belt.
Spotter - Kill 30 enemies using Sniper Support. There's no real trick to this one. As with Party Animal above, use the underboss missions if you're running low on enemies. Also, using this power will occasionally cause the game to crash, so maybe don't rely on it during story missions and the like.
Operation: Deep Sleep - Knock out 30 people with the Dart Gun. You'll only knock out three during the actual bounty hunting missions (well, you only *have* to knock out three), so you'll need to make up the rest in targets of opportunity. Just remember that you can only carry 12 darts at a time, so be ready to call for the weapons van if you intend to go on a somno-inducing spree.