Some pointers and basics before we begin:

• To finish any normal level you can use the guards and grab the lighting on their back. This is effectively killing them as far as level completion is concerned, so pickpocketing or killing every guard will open the door to the next level.
  
• You can jump out of a slide for extra momentum and speed.
  
• You can turn off enemy spawners by tapping the button on the back.

Everything else is something you should learn simply by playing the tutorial and the game itself.

All of these methods are subject to improvement for time.
Feel free to respond with your own routes!
Facility:

Purple Shift:

Safe Haven:

Trust:

Project Nova:

Volcano:

Core:
Be aware that the secret section knocks out any guards in it at the end. These are not tracked in statistics, but it is something to be aware of.
The final section is much, much easier if you simply shoot the cores instead of knifing them as I do in the video. If you are out of ammo there is a refill under the final core.

Hopefully this guide helped you get 0 kills, 0 alerts and (ideally) 0 deaths.
Don't be afraid to lower the time on every mission even further and share the results!

Hit like and comment if you found this guide helpful, it's appreciated more than you'd think!
Be sure to let your friends know about Acid Spy, it's a sorely underappreciated game.