When researching an unfamiliar area of law it is a good idea to Google around to find a legal research guide to help with your research.
Immigration Law Research Guide Example
If you don't know much about researching a particular area of law, for example immigration law, you can Google something like the following: immigration law research guide
The search retrieves a variety of useful guides to choose from. A good one such as this one from the Georgetown Law Library will provide helpful information about researching relevant statutes, regulations, and agency materials as well as a variety of secondary source recommendations.
When researching any legal issue, it is a good idea to follow a legal research process so you will not miss any legal research steps such as looking at secondary sources, using secondary sources to locate primary law, etc.
It is not necessary to follow any specific legal research process. You just want to make sure that, whatever process you use, it includes all the steps.
Click to see a useful flowchart of the process of legal research from the Loyola University law library website.