If you are new to legal research, this is a great place to start:
The American Association of Law Libraries (AALL) Legal Information Services to the Public (LISP) Special Interest Section (SIS) has updated their concise (7-page) guide:
How to Research a Legal Problem
See also the blog post, Valuable and Convenient Guide: How to Research a Legal Problem, December 4, 2009, George Wilson, at the Legal Research Plus blog.