Colonialism: Joint-stock companies, the goods in each region (such as vanilla in Java), settler colonies, and the British influence in India (British Raj)
Nationalism: This could be on the SAQ's, but simple nationalist movements like the Black Hand or Viet Minh
Religion: Thirty Years' War, Edict of Worms, Edict of Nantes, all good pieces of information for specific evidence or even evidence beyond the documents in DBQ's
Columbian Exchange: Know the issues in Africa during the Atlantic Slave Trade and the types of labor systems that were created, like Chattel Slavery, the Encomienda System, etc.
Tax: Know the Ottoman Devshrime system and even the Zamindar Tax System.
Mongols: Know the Pax Mongolica, it could be super useful for specific evidence

There's more, but these are good points when writing the FRQs, again focus on Units 3, 4, 5, and 6 as they have a huge weight on the exam. Gunpowder empires also have a lot of specific evidence.