Completing jobs and mastering them are principal components of the game. Money, loot, experience and skill points, the primary elements of the game, are your reward for carrying out Mafia Wars jobs. In order to move through the jobs quickly you must have a lot of energy.

You will find that you can just do the jobs that are open to your present character level. When you start the game you are considered a Street Thug and are only able to do the jobs that a Street Thug is capable of. The more jobs you finish the higher your level and the more job tiers you will open up.

Under every Mafia Wars jobs tier you will find a bunch of different jobs to choose from. In order to master the tier you have to master each job on the tier. You get one skill point for every job mastered.

When you master a tier you will receive additional bonuses. For the first tier, mastering it a second time will give you a five percent increase in loot dropped for that tier, master it a third time and that increases to ten percent. You can repeat the jobs as often as you like, even after you have totally mastered the tier. Later when you are concentrating on leveling you will want to go back to jobs that paid the highest experience for the least amount of energy used.

When you master a tier you also receive a new job title. The new title will appear next to you character name. Mastery of the second tier of the first set of jobs will modify your name from "Street Thug " to "Master Street  Thug ".

A boss fight is accessible on each of the first four job levels. Fighting the boss' are non-compulsory and if you decide to not do so you will not slow your progress in the game. There is a risk to these fights that is not present with ordinary Mafia Wars jobs and that is that you lose health in the fight.

In order to get some of the items for certain jobs you have to wait until you get to the required level. These items are simple to get as loot from other jobs or through purchasing.

In order to complete some of the jobs on the Enforcer tier you have to finish a job preparation that will give you the item or items required to complete the job. This job gives you the needed item and experience but no cash. For example, the Liquor Smuggling job requires that you finish the Distill Some Liquor job first. Additional energy and time is used completing these jobs because you have to do the preparation first.