How to prepare for the Russian Revolution questions?

The first thing to keep in mind is that only the topics in the syllabus will be tested. Your essay question will be based around one, or a combination of the syllabus topics. For the Russian Revolution, that would be:

- February Revolution

• Provisional Government and Dual Power (Soviets)
  
• October Revolution
  
• Lenin and Trotsky

I would always recommend approaching a topic through historiography rather than study guides or a textbook: you will write essays that are more original and you'll get a broader view of the event. Do not dive in completely unprepared, though: if your teacher has not covered the topic, it's fine to Google the basics (just use any easily digestable and trustworthy source -- never rely on Yahoo Answers, though). 

For the Russian Revolution, you actually have a shortcut: The Three Whys of the Russian Revolution by Richard Pipes is about 40 pages long (and you only have to read 2/3 of it) and covers everything that you'll ever need to know. Use whichever note taking method works for you (if you don't know how to take proper notes, you may want to start with the Cornell method) and retain the information by applying it: do a practice essay plan, draw a mindmap or write flashcards. If your teacher/tutor is nice, they will read and grade your essay. You don't need to do this right away, but make sure that you have proper notes that you can use when revising for your exams.

PS -- if you want to take it further, familiarise yourself with historians. For this topic, my favourites are Robert Service, Richard Pipes, and Orlando Figes. Search YouTube for their lectures or read their essays/books; just keep your eyes open for their bias.

Good luck!