Best tip for Lexis research is to start broad and then narrow your search. In Lexis, select your topical database, create a search string or select terms, then focus (narrow) your search until your hits become managable. Although you should always be thorough when researching your topic, you must also figure out when to stop. A guide to stopping is to recognize when you are getting the same results with each search.
Westlaw has the added feature of ResultsPlus to help you locate secondary material. Westlaw also has a Directory tab to locate databases & treatises on your topic. You can also locate keywords within your search with Westlaw's locate feature. Using boolean operators and FIELD searches also helps to narrow your results.
These databases are available to law students from the Law Library.