Stealing in AM:
Your stealing here is limited. From the outset, it is my personal (and, indeed, most humble) opinion that with regards to what skills to advance, the goal of any newbie thief should be to attain a covert.manipulation.stealing bonus of 300. Advance other things by all means! However, shoplifting is difficult and a bonus of 300 is needed to do really well : )
But back to stealing...
Each thief has a quota which is reset at the start of each quota period of 12 hours (that you are playing). This shows the amount (in AM) that you are allowed to steal. This is calculated by your guild level + $100. The guild needs to cover costs, and so 30% of all you steal (in AM) is taken by the guild. Use the command "check quota" to see how much you owe the guild, and how much space you have left to continue your thievery.
Not paying the guild its' cut will result in fines. Not paying your fines will result in large burly men dressed in leather comeing and beating you up. If thats not bad enough, after they beat you up, they steal all your hard earned cash! Persisting in not paying the guild will result in you being beaten up, having your cash and quest items stolen and, eventually, you will be killed. So paying the guild is advisable.
You can pay the guild back it's money by going to the npc Artan (who is 3w 1n from the guild foyer) and typeing "pay Artan".
When you first start out stealing, you may be caught a few times. Dont worry, just start with stealing a few pence off of beggars and work your way up to merchants, dealers, traders and, most importantly, shoplifting!
Shoplifting is difficult. Things that affect if you will be able to shoplift something are it's weight, it's cost and how many other people have been at the shop. If a shop has been shoplifted from by many other people then it will be harder to steal from it.
It is generally accepted that the best way to make money in AM is from jewellery. The best tactic is to shoplift jewellery which is in bad condition, get it fixed up, then fence it when it is in excellent condition. In this way, you will pay 30% of it's original price to the guild, which will be low due to the items low condition. Then you can get as large a profit from the item as possible. For example, take a random ring in poor condition. It will take, say, about 50p from your quota, meaning you pay 30% of 50p to the guild. In excellent condition you might get $5 for this ring from Sol if you have a bit of other.valueing.jewellery. That said, if you can't find resonably good items in poor condition in shops, money straight from NPC's (merchants are best) is your next best option as you will only lose exactly 30% of it to the guild without losing any money due to getting low prices for your gear.
Even if all of these tactics leave you dry due to lack of targets, shoplifting jewellery in good condition is not too bad a way of making money, you will still make a decent profit.
Stealing outside AM:
Once your quota has been reached, there are a few more very profitable places just crying out to have their economies stimulated! Probably the best of these is Sto Lat. The best way to make money in this town is shoplifting.
It is against the law to steal in Sto Lat, and if you do so and a Royal Guard catches you, he will throw you in jail. So the best thing to do is watch where you go and try to either sneak past them, or avoid them completely.
The best things to steal in this town are: Jewellery, backpacks etc from the bag stall in the market and wallets from the wallet store in the sw corner of the market. Also, tulips from the flower shop bring in a very good return. All of the wallets and purses from the wallet store are worth taking, especially the most expensive ones. Stealing all the black and large backpacks from the bag stall will also bring in a tidy profit. The best jewellery store to steal from is the Rock-A-Rama store. However, this place is very difficult to steal from, so much so that I don't usually bother to go there except straight after a reboot. It is possible to make heaps of money from there alone if you pick the most expensive items you can steal. With a stealing bonus of 500 I generally go for things priced at around one platinum coin and change while in this shop. This is not a hard and fast rule, it it possible to steal the most expensive item from here (Lapis Lazuli pendants) with a lower bonus, it all depends on how many other people have been at the shop.
Now we move on to stealing in OC! It used to be possible to make three royals in 15 minutes in this place, but since the changes to prayer beads this is sadly no longer possible, however OC is still worth a visit for a bit of thievery.
One good place is the alchohol shop. Shoplifting is a difficult activity and I recomend a co.ma.st bonus of 330+ before attempting the alchohol shop. This shop is located on the east side of the OC market and can be entered with "enter stall". Once here the best things to steal are Scumble (most difficult), Vodka and Whiskey. If you fail on these more expensive items then try cheaper ones. If you "feel you have stolen enough" then simply go to the weapons shop, steal a few of those items, then come back!
The last good place to shoplift are the temples. It used to be possible to make $250 in a short space of time from the temples alone but alas, the amount of money that holy items fence for has been downgraded severely. Still, it's worth a visit. Grab the beads and books, these each fence for about $7 (it used to be $20-$30 gnah gnah gnah!) apiece. If your stealing is not high enough for these, grab all the symbols and amulets as these are also worth taking.
Hillshire is also a tremendous place to steal, as most of the NPCs are carrying a lot of money and rings which can be fenced. Also, the Silver Star Boutique has some good expensive items that are resonably easy to steal. And if you wear them, they make you look very swish indeed.
That said, the only way to get money out of your shoplifted items is to fence them to a fence (shifty jim, Sol, etc) as shops will not deal in stolen items. To do this go to the fence and type "fence **item** to **fences name**" For example "fence ring to jim". A list of fences can be found here. To get the best prices for your stolen items, advance the other.valueing skills.
Being hidden may make your stealing easier, as may 'sneak high'. I can not confirm any of these as I know nothing about code, so it's probably best just to do both, it can't hurt : ).
Now go forth, and stea...*ahem* redistribute!