For most people the first terrorist hunt they will try to complete is Kill House, being the first mission on the list. I recommend this level for the following achievement for the following two reasons;
1) It is a small map where the terrorist enemies take 3 different routes on the map allowing them to fall into 'kill zones'.
2) It is one of the maps with a smaller enemy density at the low setting consisting of just 15 enemies.
These two points allow you to fully exploit the map and breeze through the level first time (in theory).
As far as outfitting goes you should wear the armour that provides the most protection for when you get shot at. In regards to weapons you should use whatever suits you as it is useless telling you what weapons are best if they don't compliment your own playing style.
For myself however I more often than not went with a G3KA4 with a 6x scope & a SPAS-12 shotgun with a rifle scope. This allowed flexibility for long, mid & short range combat, along with flash bang & smoke grenades as a dirty ace in the hole should things get desperate.
In terms of settings, I went through all T-hunt missions on realistic, with low density & had my AI squad mates with me, despite their stupidity they are invaluable if you are unable to find some friends to play this game with.
As for placement for Kill House I immediately ran up the stairs sent my squad up the stairs on the left to the top floor of the building whilst I took cover on the right wall allowing me to overlook the right side walkway and any fast ropers. Most of the time your AI team-mates will clean up 10 of the 15 enemies while you sit back and pick up the easy kills. In all this should take between 1:30-3 minutes to complete this level.
As a general tip if things are too quiet look behind you to make sure you aren't being flanked from below, if clear continue to fire some shots down the line to shake the proverbial hornets nest. That's all I can really recommend, if you did this or any T-Hunt mission on realistic this should net you the following achievement as well.
And with that you are on your way towards
Happy Hunting!!! All feedback is welcome.