Start with something that interests you. It's much more difficult to write a paper on a boring topic.
A good historical question requires an answer that is not just yes or no. Why and how questions are often good choices, and so are questions that ask you to compare and contrast a topic in different locations or time periods; so are questions that ask you to explain the relationship between one event or historical process and another.
You will often begin by selecting a research topic, then defining a research question within this topic to investigate. What's the difference?
A simple topic is too broad. For example:
A research question must also not be too narrow.
As you explore scholarly secondary sources and historical primary sources, you may need to periodically re-evaluate your research question to ensure that it is neither too broad nor too narrow.
A good research question might:
Source: Williams, Robert C. The Historian's Toolbox: A Student's Guide to the Theory and Craft of History. Second ed. Armonk, NY: M. E. Sharpe, 2007.