I did the whole thing on the first day. Pick pocketting. Attacking npcs to get drops. Rifling through stuff for green+. After a day I found that the safest thing, with the highest payoff, was just running around and looting stuff. Even the locked boxes were easy. Caught unlocking was 8-12g. It's when you actually loot the thing that the costs go up. So you unlock, wait to be hidden and bam. 1-3 greens or even a blue.
Killing npcs has risks. Pickpocketing has risks. Burglering houses? Not so much. I mean I walk around in the open rifling through boxes, bags and trunks in plain view with no notice given. Find something nice, crouch and wait for the eye to close. Quick E -> R button presses and bam, it's in my pouch in less than a second.
The sneak mechanic needs a few tweaks. If you're in the view of an npc, you can't couch and suddenly vanish. IE: Can't hide while in npc view.
If seen inside of a LOCKED house, I would surely keep my eyes on him and tell him to get the hell out. Not quietly watch him rifle through my stuff.
I think there should be an extra stage. You've got Green, I'm an upstanding citizen, then Red, CRIMINAL!! They should have a yellow stage, or watchful. Like unlocking a lockbox and getting caught should put you in yellow, the npc would not look away from you and repeatedly tell you to get away from it. If you don't the warning would go up until it reached the stage where they yell for guards.
The guards... yea. They respond to things they see. I tested it, robbed a guy in plain view of the npc but behind the guard and he didn't do anything. There should be an AoE when an npc calls for the guards. Any guard in listening range will rush to the npc and target the player who triggered the shout. If the npc is inside of a house, have locations like the door and windows were the shout will ping outside and if a guard is near that location will rush inside.
A side note, unarmed npcs that get attacked shouldn't fight back. They should run away screaming for help.
This would make being a robber more fun and challenging.
(PS: Has anyone found anything rare green+ inside of a Keg? I haven't.)