The One Sith operates as a totalitarian state, with the Dark Lord making all decisions and his followers obeying without question. He is advised by his Council of Brothers, an analog to the Masters' Council of the Jedi Order. When the Dark Lord dies, the Council of Brothers communes with the Force within a temple on Endor to determine the identity of their next Dark Lord. Beneath the Council of Brothers, the One Sith are organized into three tribes of equal status:
The Tribe of Shadows
The Tribe of Warriors
The Tribe of Seekers
The Tribe of Shadows operates as the quiet steps and quick hands of the One Sith, relying on cunning and subterfuge to accomplish their missions. They are trained from apprenticeship in the arts of deception and stealth.
The Tribe of Warriors is the largest among the One Sith tribes. These Sith are especially trained in the art of combat with light-weapons, as well as vehicular combat and piloting skills.
The Tribe of Seekers is the smallest of the three tribes. They are dedicated to the pursuit of knowledge, planning, intelligence and "recruitment" -- a process in which they steal away the young from unsuspecting citizens across the Galaxy to raise and train as One Sith.
Among the three tribes, there is also distributed a number of former Sith Empire followers. Most of them occupy low-level positions with the Tribe of Warriors, as the One Sith consider them nothing more than cannon fodder. The One Sith do not discriminate based on species or race. All followers of the Dark Lord are equal under his gaze.
For decades, the One Sith waited beyond the fringes of known space, observing as time and time again the Sith Empire failed to bring about the total and utter annihilation of the Jedi Order and their Galactic Republic allies. When the Sith Empire was destroyed, the One Sith recognized their time had come and commenced preparations to make their presence known to the Galaxy.