Choose a topic.
Do a brain dump: Note down what you already know about your topic, including
Fill in the gaps in your knowlege: get background information from encyclopedias or other secondary sources. Wikipedia can be good here.
Select the best places/ databases to find information on your topic. Look under the History Databases tab of this guide for article database suggestions. Or use a catalog like Oskicat or Melvyl to search for books and other resources.
Use nouns from your brain dump as search terms.
Evaluate what you find. Change search terms to get closer to what you really want.
Refine Your Topic - Using the information you have gathered, determine if your research topic should be narrower or broader. You may need to search basic resources again using your new, focused topics and keywords.