First, find background material on the countries, regions or legal systems you wish to study. This will help you understand context for your research and discover the right vocabulary for developing search terms. These resources may also point you towards relevant primary sources.
Encyclopedias, dictionaries and research guides are good starting points that provide overviews of foreign domestic laws and systems, as well as suggestions for where to continue your search.
The following texts are excellent resources for understanding legal systems of the world. You can also check JuriGlobe - World Legal Systems, an online resource by the University of Ottawa Faculty of Law.
Start your research by looking for basic information about a country's economy, political system, government, and legal history. Some suggested sources:
A number of law schools and other institutions have gathered resources into research guides, often with references to sources of specific domestic law.