Dungeons and Dragons Thieves Guild ideas?

One of my PC’s has expressed interest in running a thieves guild. It sounds fun, but being a lawful good person in real life and only having a guild for my players to sell their stolen goods I haven’t a clue as to what the daily operations would be and other things that would be involved beyond having a fence and doing miscellaneous stealing and break-in missions. I have some experience with video games (such as Skyrim) but it seems a bit limited when it comes to all of the events going on in the background. Any ideas?