For some research questions, finding the appropriate secondary source on a topic is sufficient. If your goal is to learn the definition of a legal term or understand a basic legal concept, you can consult a dictionary or encyclopedia and successfully answer your question.
If you would like to learn more, you can continue on to use other secondary sources for more depth, or you can read the primary materials cited in the secondary sources.
If you are using secondary sources to find primary law, it is very important to make sure that the cited law is still up to date. This process is called updating, and it can be accomplished with a citator tool like Keycite or Shepards. These tools will inform you if a judicial decision has received negative treatment, or even been overruled since the secondary source was published.
You can also use the primary authority cited to find authority on similar topics in different jurisdictions. Many secondary sources are non-jurisdictional or primarily federal, so this can be an essential step to finding authority that is binding in the relevant jurisdiction.
Further review of the primary sources may reveal new research questions, and it is often useful to cycle back to secondary resources again to answer those questions. In large and complex legal research, you may return to secondary sources several times to address different issues as they arise.