Foxiest of the Hounds

http://www.xbox360achievements.org/game/deus-ex-human-revolution/guide/

 

This is the achievement where you'll need to make sure you don't make any mistakes when trying to avoid being caught. First off, I recommend you save often to save any heart ache. Save once you get to a new area, save when you get past a tricky spot even if you're still trying to pass it, save before hacking etc.

Next up you'll want some certain Augmentations to help make this a smoother ride. Most are listed in the Roadmap above, so please refer to that. The main one that will save you from getting spotted is the Skin Augmentation - Cloaking System. With this and some quick recharge you can bypass a whole area with getting spotted or worrying about movement timing. 

Now onto the things you don't want to do:

• * Never make a guard, camera or turret turn Hostile. If this happens, reload a last save. Having anything Alerted or Suspicious is fine.
• * When hacking a turret, don't make it turn against anyone. This will count as kills and sound alarms.
• * When you knockout anyone, hide the bodies. The last thing you want is a guard or camera spotting them and setting off an alarm.
• * Save before you hack. If you mess it up, they will lock down and may set off an alarm.
• * Some areas in the game it'll automatically go into a Hostile state. This is is fine so don't worry. It normally happens after a cutscene and that you're in the surrounding area, so it's part of the story. But be warned, you'll actually start these bits without actually being seen, the AI just know you're about! Just get out of the area without actually being spotted and you should be good to go.

Good luck!

that sounds like a bunch of hard work ...