I have a group of PCs who want to play criminals. I ruled out letting them be chaotic evil super villain types but said I'd be open to letting them play as mob kind of players working their way up through waterdeep. 

Any ideas for criminal missions? I'm trying to get them to a point where we can do. A home brew spelljammer  story. 

I want to start like a GTA game and start with little petty crimes and have them pull bigger and bigger heists until a mob boss sends them on a huge quest that they can either do for him or take on the quest for themselves. 

I need help coming up with the beginning missions. 

Running collections?  Getting payments for the local bookie or loanshark?  They'll have to intimidate or torture, but definitely not kill since then no one gets paid. 

Doing a shakedown?  Going from business to business offering, "protection" and them vandalizing or beating up patrons of all the businesses until they get paid. 

Smuggling?  Fixing sports competitions?

Racketeering?  Find something on a business owner.  Maybe they have gambling debts that you or your boss can purchase.  Then move in and threaten him to use their business as a front.  

Depending on how evil you want to get.  Human trafficking?  Drugs?  Prostitution?  Underground fight clubs?  So you'd have to go around, "recruiting" and then staging fights?  

I mean with Godfather's 1,2,and 3, Goodfellas, and Scarface I'm sure you can pull something out of those movies.  Will they be like the Flash's Rogues who have a code of ethics and are all about the score or amoral, will do anything for a buck, scum? 

I think your players want to play Shadowrun, not D&D lol. Seriously any mob type situation is going to go into a chaotic evil super villain land. With that said, you can steal a lot of ideas from Shadowrun. Stealing certain things from nobels and such can be a good way to work their ways up. You can even have goblins having had stolen the item already and now the PCs have to go on a dungeon crawl to get it back.

They can plant evidence to frame someone. They can brake someone out of jail. They can plot to make a mayor candidate lose the election by whatever means they come up with.

Quote from NightsLastHero >>

Seriously any mob type situation is going to go into a chaotic evil super villain land.

There might be examples to the contrary, but I still feel like any PC who wants to play this type of game is quickly going to go the not so play by the rules route. 

And it doesn't have to be the focus of the entire campaign, but it sounds like it's what your PCs want.... 

I would agree that unchecked, it will get all murder-hobo-ish, but that's when the town guard get's sick of their crap and you get to host a TPK.  

I do acknowledge the challenges you're talking about, I just think that if you're committed to doing this, consequences need to be implemented to keep everyone on track and let it not descend into just running around punching pedestrians like in GTA.  

So you annoy the town watch, they throw you in jail.  Don't bribe the right officials, off to jail.  Do something so dark that the lawful good deities might take notice and Goody McPaladine will show up to crit their faces.  

So just because they are running an evil campaign, doesn't mean they get carte blanche to run around and do whatever.  

I'm thinking of letting them be criminals for a bit and when the heat gets too high a crime boss sends them on a mission outside of town which they can do for the boss or try to make the quest their own. 

How do they see themselves or their characters?  A lot of people go into crime because they feel the system is rigged against them and if they were to live honorably, they would suffer.  In the D&D world, races like Tieflings, Half-Orcs, and Drow would probably feel this the most.  Are they somewhat patrons to a slum or something like that?  you know, they get their cut, but they do some of what they do to help out friends and family who can't/won't go down the criminal path.  Especially in Waterdeep, Lords and the wealthy are really born into their positions, and outside of dumb luck or hard work, it's not likely that everyone is going to make it to a higher social position.  If you make the reason that they're criminals a more of a Robin Hood type of backstory, they're less likely to go chaotic-evil or murder hobo.

That's brilliant!  I hadn't thought of that.  Your PCs backstories should enlighten you as to how they're approaching this.  Are they poor kids or orphans just struggling to survive?  Maybe they just got sick of being kicked around separately and have formed their own gang?  Were they born into it like La Cosa Nostra?  

Doing a pirate game set in Eberron myself. The PCs aren't heroes but not evil. Their just starting out and looking for jobs so I put forth some rumors and had them approached by shady individuals that see them as a possible resource to he exploited. There was also a good thing to do helping out one of the Dragonmarked Houses. 

So the hooks were the Dragonmarked House's establishment was burned down. Someone is looking for a ship to take an unidentified cargo, No Questions Asked. Pilgrims of the Blood of Vol are looking for transportation to Karrnath. They manage to work all three into ways to profit. They have reason to believe the Pilgrims are Emerald Claw agents that burned down the building with a strong alchemical fire compound. The crates are the compound and they took their money and are going to turn on them and turn them over to the authorities in Karrnath for a reward.

So, with my example above, I suggest, if you're comfortable with this style of running, to just come up with some loose ideas and let the PCs run with it. Give them plenty of rope to hang themselves.