Pretty much anything by Michael Parenti is great for people who are starting to educate themselves. Lenin is great as well, in particular I think these three books are essential reading:
- The State and Revolution explains how capitalist democracies are organized and why reformism does not work
- Imperialism, the Highest Stage of Capitalism explains how capitalism evolves over time and the tendency towards monopolies
- “Left-Wing” Communism: an Infantile Disorder explains principled ways to organize and build a movement based on the experience of the Soviet revolution