The three most important books that new Marxists should read in my opinion are:

• The State and Revolution
• Imperialism, the Highest Stage of Capitalism
• Left-Wing Communism, an Infantile Disorder

The State and Revolution does an excellent job explaining the inherent problems within the capitalist democracy and why reformism is a dead end approach. Imperialism exposes the dynamics of the capitalist economics and how exploitation is a fundamental aspect of such economics relations. Finally, Left-Wing Communism reflects on the experience of the Russian revolution, and explains how to find the proper balance between idealism and pragmatism. It explains the tactics communists should use, where they need to stand firm and where they can compromise.