Some beginning legal researchers ask which secondary sources are "the good ones"— the ones they should always turn to first. The answer is that it depends on what you need.
As you work on research projects, you'll develop a sense of what sources are most effective for different types of questions. Through reading and using different sources in your life, you've learned that People is more likely to interview Oscar winners than Sports Illustrated is. Now you will learn through using them which secondary sources in law will work best for your different questions.
Here are some generalizations about what sources to try for different needs:
For definitions of legal terms
For very recent developments (cases, legislation, etc.)
For recent (but not too recent) developments
For scholarly analysis
For overviews of broad subjects
For citations to cases from around the U.S.
For discussion of Washington law