Month and a half isn't that necro. It's like the zombie that all has all its skin, teeth and hair.
Back to the actual topic, playing as a thief is going to be quite challenging, but potentially very rewarding, if done right. The committing of the crime itself will likely be the easiest part. Sure, there is the risk of someone spotting you as you break into a building, but any smart thief should already have scouted out a good entry point and be familiar with the guard patrols.
An important consideration is where you intend to operate. Thieving within the settlement that you live will only likely be sustainable in the largest of cities and still brings many risks. The other option is to live in one settlement and travel to other nearby ones. The farther you travel, the harder you are to track down, but also the more time you have to invest. That's not even mentioning the risks you face during travel. Nothing worse than making a big score, only to get rolled by bandits on your way home.
This brings us to how you'll actually sell all these stolen goods once you have them. If you're thieving in other settlements, you might be able to just sell to your local merchants, depending on the goods. However, if stolen goods keep popping up in a particular settlement, attentions from law enforcement is going to focus there rather quickly. Bad for business. So what is a thief to do?
Find a fence. A fence is simply a merchant who doesn't mind dealing with the moral and legal implications of stolen goods. A network of such fences would work best, though a wandering merchant could do quite well in the fencing business, assuming he knows who to buy from. Buy stolen goods in one area, at below market value, of course. Travel to an area far enough away that said goods won't draw attention. Profit. You'd want to maintain some legitimate business at the same time, as cover.
A network of fences would simply be an expansion on this idea. A local merchant in each major settlement could buy stolen goods under the table, then resell them to a traveling merchant, perhaps in trade for stolen goods from a distant settlement.
To sum up this rather lengthy post, aspiring thieves should be less concerned with how they can steal things and more with the logistics of what to do one they have said things. A lone thief roaming around grabbing whatever they can it's going to have a short, less than lucrative career. A smart thief, who works with the right network of people may someday be as rich as a king.