The U.S. has a federal system of government, meaning that there are separate federal and state governments that share law-making authority for the same geographic territory. Both the state and federal systems have three branches of government: legislative, judicial, and executive. Each branch is a unique source of law.
In evaluating legal authority, a researcher must consider if that authority is mandatory or persuasive. Researchers must also be able to identify primary and secondary sources of law. Primary sources of law issue from a law-making body and are, in essence, "the law itself." Primary authority can be either mandatory or persuasive. Secondary sources comment on or explain the law. Secondary sources are always persuasive, rather than mandatory, authority.
Before you begin any assignment, you should know some basic preliminary information such as what the final work product should look like, how long you have to complete the assignment, and if you have any restrictions on your research such as not using certain subscription databases. You should also try to find out if the assigning individual can point you in the direction of any helpful terms of art, any individuals who can help, or any internal written documents or templates that may be useful.
You should try to make a habit of writing out the issue or issues that you are being asked to research. Being able to articulate your research goals is important.
There are various ways of keeping track of your research and taking notes. Do what works best for you. That might be a written checklist or research log, or it might entail using electronic resources such as the folders and search history features in Westlaw, Lexis Advance, and Bloomberg Law. It could very well be a combination of these techniques.
When selecting keywords to search, you need to consider the parties, places and things that may be relevant, potential claims and defenses, and the type of relief sought. You also need to consider whether you want to focus on the specific facts of your situation or on the broader potentially applicable legal doctrines.
There are two general types of searches: terms and connectors searches and natural language searches. Terms and connectors searches offer more control, but might result in missing information. Natural language searches are similar to a Google search where you don't have as much control over how the database processes your search. Indeed, you may have very little understanding of how your search results are being produced. Natural language searching produces highly variable results across various different databases.
Both Lexis Advance and Westlaw Edge provide Advanced Search Menus, which help you craft a properly targeted search.
When you are reviewing your search results, remember that you can usually filter the results by year, jurisdiction, keyword, etc. You can also change the method of sorting results. For example, most databases present the most relevant results first, but you may want to change the display to show the most recent results first.
Finally, keep in mind that searching is a process, not an event. Often, you will need to refine your search more than once.