Here is a great list from law.com for all you summer and new associates. The articles goes into more detail but here are the basics you should know:

1. Civics 101.
2. Never start your research with Lexis and Westlaw if you are clueless about the topic at hand.
3. Cite checkers such as Shepard's or Key Cite are much more than case validators.
4. Efficiency in searching Lexis and Westlaw is essential.
5. Boolean searching is more precise than Natural Language searching.
6. Everything does not have to come from the Internet.
7. When to stop when performing Web-based research, free or fee.
8. The limitations of both Web-based research services and print resources.
9. Asking the partner or senior associate for clarification is OK if you are confused or unsure of the assignment.
10. Asking your firm law librarians for help is encouraged and expected.

Source: Law Librarian Blog