What Techniques did Joseph Stalin use to strengthen his power in the Soviet Union following Vladimir Lenin's death?

(apex) he exiled and executed huge numbers of political enemies

Joseph Stalin is a textbook dictator that was not choosing means in order to strengthen his power and control of the country. Stalin's tactics were mostly consisted of fear, elimination, and imprisonment. In order to avoid and confrontations and strong political opponents, Stalin eliminated pretty much everyone that his people were able to capture and was posing a political threat to him in his eyes. These people were either killed in cold blood, or were taken in the Gulag where they died because of the terrible conditions. Everyone that was going to express an opinion against Stalin or the Communist Party was targeted and was ending up in prison, usually never coming home again. In order to nullify attempts for separatist movements, which was highly possible considering the numerous ethnic groups in the Soviet Union, Stalin was systematically killing, imprisoning, or relocating people of certain ethnic groups in order to break their nation core and identity.