The Sith Order of Darth Advent was a Sith revival group. They believed the the Rule of Two based Order of the Sith Lords was doomed to die out, and that the teachings of the Ancient Sith Lords needed to be restored. The Rule of Strength was the philosophy to be followed to the letter, and failure meant death. All Sith would bow down to their superiors, become stronger and overthrow their masters, or die trying.
Sith Adept (Younglings)
The Sith Adepts were children who would be abducted from their home, usually with their parents killed, and indoctrinated in the ways of the Dark Side in one of several Sith Academies. Once they were old enough, the Trials of the Sith would begin.
A Sith Acolyte was the apprentice of a Sith Crusader. An Acolyte would learn all he or she could from their master, then challenge them to a duel. If they won, the Acolyte would become a True Sith. If they lost, their life was forfeit.
The Sith Crusaders were the true sith of the Order. They were the ones who hunted Jedi, and conquered planets. They were encouraged to take apprentices, because they were Masters of nothing without an Acolyte. They would delay the training as long as possible. But that fateful duel is only inevitable...
A Sith Crusader who had won a duel to the death with another Sith Lord was granted the lord status. They were given the "Darth" honorifc and a title. They could also become a member of the Sith Council, where they could challenge the reigning Dark Lord to a duel.
Dark Lord of The Sith
The leader of the order, and the strongest member. They rule Sith Space with an iron fist, and seek to retain their title for as long as possible. The current Dark Lord is Darth Advent.