Skyrim:The Dark Brotherhood Forever

Quick Walkthrough
# Approach the Night Mother.
# Speak with the contact.
# Kill the target.

Detailed Walkthrough
Keeping the Faith
After the events of Hail Sithis!, the Dark Brotherhood  has new headquarters to improve and maintain. As the Listener, your responsibility is to heed the Night Mother and continue to fulfill contracts. 
For this recurring quest, approaching the Night Mother will initiate a dialogue: another child has prayed to their mother and performed the Black Sacrament, securing another contract for the Brotherhood. 
Travel to the specified location and speak to the client who will give you a name and location of a generic NPC that he wants eliminated. The client will pay you the money up front. Travel to the location and complete the contract. Return to the Night Mother for another contact as needed or desired. 

Contact the Client...
The client will be one of ten randomly chosen citizens who performed the Black Sacrament. None of the contract givers exist prior to the quest:

...Now Find the Target
All contract givers share the same dialogue and will spawn a randomly chosen target from the following dialogue options: 


Notes
The targets that you are supposed to murder never sleep, and almost always stay in crowded areas. This can make it very difficult to kill them without incurring a bounty. One possible way to accomplish it is to hide a safe distance away (remain in sneak mode and make sure the eye is totally closed) and then send a follower to kill the target. Run outside the area in question while the crowd is retaliating against your follower, and then fast travel out of the hold. Your follower will fast travel with you.
All targets have 50 health. Plan your assassination tools (such as poisons and weapon choices) with this in mind.
If the recently killed target is reanimated and subsequently turned into an ash pile on their "second death", the next time they are randomly chosen as a target, both the NPC and the ash pile will appear. Attempting to search the ash pile will cause the NPC to speak. Sneaking and searching the ash pile qualifies as pickpocketing.
Sometimes if you reactivate (or talk to) the contact while they are still talking it will cause you to get paid twice.
Sometimes you can intimidate the target when talking to him. This can cause him to attack you, and the surrounding people will try to kill him. If they kill him, the quest will be complete and you will not have a bounty. The target can also try to flee; in that case, chase him into a secluded area, and then kill him.
Pickpocketing a target will never work, no matter how high your Sneak and Pickpocket skill.
A good idea is to kill your target at a distance with a bow, or get up close and personal with a dagger. Bows are useful for crowded places while daggers are better for more secluded targets.
With high sneak and archery skill levels and a strong bow, such as the Enhanced Dwarven Crossbow, you can kill any assigned target in one shot.  Wait until dark (if outside) or find a shadowy corner and go into sneak mode to do so undetected, then simply walk away.  You may find that this makes the quest too easy, however.

Bugs
 

Quest Stages