These are just a few tips I can think of right of the bat. Close hacked unlocked safes in the detroit area during your first visit for extra hacking opportunities during your second visit. This is something a lot of people might miss. Get turrets and robots even after deactivating them for extra Xp.
After clearing out an area remember to go back and explore every possible pathway. Hack everything in the game, including alarm panels which can be easily missed. If it is difficult to do so in a particular area swarming with guards, bypass all the guards, get the ghost bonus and then come back and takedown all the guards. Always try to get a ghost bonus/smooth operator wherever possible. Try to get a multiple takedown on guards having conversations or even patrolling. Try to do a non-lethal takedown on every possible guard.
You have to go for a non-lethal run (pacifist).
This image showed up on Reddit this morning demonstrating a perfect score:
