Let's start with the good news and bad news:
Bad news: This achievement can be very annoying if you underestimate the amount of steps it takes to get through this.
Good news #1: It will definitely aid you in the rest of the game learning how to hide from being spotted.
Good news #2: Once you are detected enough times, you can run through this level in just a few minutes all at once for the achievement. I am thankful for the RB to skip many sequences. Also, if I heard that phrase "We're gonna get...caught" one more time, I may have taken a hammer to the game. Yeah, bad news #2, the acting sucks in many points. :)
There are several places to avoid detection
- The "Stalker" achievement (getting the meds in the boiler room)
- Hiding in a locker while Teets sells out
- Following Billick in the hallway, and the pass off of the envelope to a coworker
- After unscrewing a duct (tutorial), up the end of a stairs, another locker to dive into and a guard getting coffee (will be in the room behind you). You also learn of a guard that can't keep it in his pants, apparently.
- After going up the shaft, you'll see the before mentioned guard making his moves on a woman, this is where you grab the envelope
- Another guard as you climb down (this one was tricky for me at first). Wait by the doorway for him to face the wall on the opposite side of the room, then head for cover towards the middle of the room. He'll head to the door, then swing out of sight from him. Once he passes you, you're free to creep past him with his back to you
- A camera after the last guard
- After some messing around with climbing (and a quick action with the elevator), one last guard. You won't avoid him once, but twice. Yes, another locker is involved.
Once you get to the fight in the showers, you're clear to go. Achievement will pop after it begins loading chapter 2.
If you get detected, don't keep restarting, just learn how to get past each guard, and then go back and do the whole level from scratch.
I did the "dashboard out" trick, which didn't work for me. But thanks to the RB, and how quickly the game can progress, you can knock out this level pretty quickly.