In Deus Ex: Human Revolution for the PC, PS3, and Xbox 360, there are a lot of different ways to earn XP to level up your augmentations. Some can be a little more rewarding that others though, so which paths are the best to maximize your character?
Use Stealth
The Stealth path is by far the best route for better XP, since you get much more XP for takedowns than you do for kills (example, 10XP for killing a guard, 20XP total for killing a guard with a headshot, vs 50 XP total for a non-lethal takedown).
Not only do you get more XP for takedowns vs. kills, but you also get bonus XP at the end of each level for Ghost and Smoother Operator. Ghost (500XP) is accomplished by not being spotted by any guards at all, and Smooth Operator (250XP) is accomplished by not raising any alarms.
To accomplish these, you need to be good at the following:
Hack Everything
Hacking gives you a fair amount of XP, so bump up your hacking skill and hack everything in sight. Using codes to open doors and safes and using passwords to access computers doesn’t give you any XP at all, so hacking is the best way to go to maximize your XP earned.
Explore Everywhere
Finding secret areas gets you XP, so search every nook and cranny for doors, vents, etc. A lot of buildings have back doors you can use to get easy XP.
Look for Ebooks
There are 29 Hugh Darrow Ebooks scattered around in the different levels of the game. These grant you 200 XP each just for picking them up to read, so find them all for a nice 5800 total XP earned.