A good topic (sometimes called a "research question") is neither too broad nor too narrow, and it shouldn't be a straightforward factual question. Below are some poor topics/research questions and how to improve them.
- Climate change. This is far too broad - no assignment or dissertation could cover such a broad topic well. A more narrow topic could be "impacts of mosquito-borne illness due to warmer temperatures."
- Where did hip hop music originate? This is a type of factual question - there's not much to discuss here (unless there's sizable debate over the answer). A better topic/research question to discuss would be: "How have hip hop music and fashion co-evolved"?
- Why do people like wearing Birkenstock sandals? Consider whether there is likely to be any scholarly material about a topic like this - chances are, there hasn't been academic research on such a topic. A better topic might be "cultural changes in footwear over the past 100 years."
- Success of Six-Sigma training opportunities in a veteran population working in supply-chain management. This topic is too specific. A broader topic would be "Six Sigma training's effect on women's health."
Don't worry too much about nailing down the perfect topic or research question right away. Chances are, once you start searching, you'll need to modify your topic or research question.