One topic that is key on the Russian History unit is on the topic of the consolidation of power, 1917-24. This is a topic that AS students tend to find intimidating, though in reality it need not be so complicated.
The key is to realise that the answer lies in connecting all of the topics that you already revised, such as War Communism and NEP, and using them to explain how the Communist government maintained its hold on power. The notes below cover the main points, though not the detail. Therefore you will need to have your own notes to hand to fill in the gaps with detail where this summary links key issues together.