Here are some details.
1. Where?
Assassins have hideouts. Some are famously known, like the one in the Zenotharian capital of Thebas, which is located underneath a brothel. Others, like the ones in other parts of the wolrd, are completely unknown. Each entrance has the Assassin's symbol where a dagger can be stabbed into. This dagger unlocks the door.
2. Who?
Assassins are ranked as below:
1. Guildmaster - Top dog of the Assassin Order
2. Generals - The Guildmaster's attendants, leaders of the guild
3. Assassins - Typical assassins, officers of the assassin army
4. Guardlings - Typical assassins, soldiers in the assassin army
5. Backers - Researchers, Medics, etc.
6. Underlings - Assistants to the above
7. Acolytes - Keepers of information