Thief Guide

With the new Justice System you can now become an Outlaw and make a profit from thievery and other mischief. No longer are all the houses and other public containers around cities yours for the taking however, that does not mean there inaccessible. Here's my simple guide taken from a range of online sources on the art of thieving.
(Shane Scarbrough, @mymaserati91)

Basics of Thieving

Since the update you will notice that some NPC’s will have a grey glowing effect around them, meaning they are a neutral NPC that is apart of your faction.

If you are not careful and start swinging your weapon or using any abilities in a populated area it is very easy to accidentally attack innocent NPC's resulting in the local guard to soon be on your case and if caught, will make you either pay, or attempt to kill you if you flee.

There is also the option to pickpocket NPC’s by entering Sneak Mode. On approaching an NPC in sneak mode the chance of success shown, as well as the difficulty. It is good to wait until the chance turns green as failure can attract unwanted attention so be sure you have a good chance of pulling it off and the area is clear of guards.

Guards are un-killable, this is to prevent total “chaos” over cities, however it is possible to murder NPC’s, and will typically result in a much higher bounty than opposed to pickpocketing. This will attract more attention to you and likely start a brawl between you and NPC’s or Guards.

Houses can also be broken into and doing so can open up new opportunities to find rare goods. you can search through desks, end-tables, personal chests, and on the odd occasion you might find a private strongbox with nice valuables. Strongboxes are not only found in houses, they can be found in banks, around trader kiosks and other typical places for valuables.

There are four categories for Bounties:

1. Upstanding — You have no bounty on your head.
2. Disreputable — A small bounty, Guards may stop you if approached.
3. Notorious — Guards are on the look out for you, and may chase you.
4. Fugitive — Guards will kill you on sight.

Any stolen goods you come across can only be sold to a Fence found in a local Outlaws Refuge in any city, fences also offer a”Launder” option of stolen goods so they can be used instead of fencing them. Outlaw Refuges are also a safe hiding place while you are avoiding Guards, you can also pay off your bounty WITHOUT losing your stolen goods, if you decide to do so.

Tips for Better Thieving 

Thieving is Risk versus Reward, so try to keep the risk low. Killing innocents has far more penalties than benefits, you will be able to loot items from the victims body, but it will likely be worth less than the bounty you just occurred. 

Be ready for escape. There is the chance that you will be spotted and chased down by the Guards. If you have a pre-planned escape route, you’re much more likely to get away if things get out-of-hand.

If you are killed by a Guard, you will have your bounty taken from you by force.  So not only did you pay the fine, but your armor will be damaged.

Its also worth noting that any Gold that's hidden in your bank will NOT be taken if caught by the guards, so keeping very little Gold on you is a good tactic for Thieving, however it will only partially remove your bounty, and you will not be upstanding.

As you go into higher level areas for thieving, you will find access to more valuable goods than before, at the same time acquiring a higher bounty from being caught committing crimes.
As you do lockpicking, pickpocketing, and other various Thieving activities — you will gain skill in the Legerdemain section.

Skill points can be invested into this tree for the following:

1. Improved Hiding – Reduce Stamina cost of Sneaking. (great for Cyrodiil)
2. Light Fingers – Increase chance of pickpocketing.
3. Trafficker – Increases number of stolen goods you can sell per day.
4. Locksmith – Increases chance to “force” locks
5. Kickback – Reduces the fine of bounties paid willingly

If you plan on doing a lot of Thievery, this is a good set of passive skills to spend your points on. It will also increase profits, and reduce your chance of being caught, as well as the penalties for getting busted.