When you approach a research topic on foreign or comparative law, your first step should be to use secondary sources to acquaint yourself with the characteristics of a foreign legal system or comparative law sources and methods.
Secondary sources provide commentary on a legal issue, put the legal issue in context, and provide a summary of the relevant legal documentation.
The biggest benefit of using a secondary source for foreign and comparative research is that it will lead you to primary sources that -- unless you're already very familiar with the country's legal system and the types and relative weight of laws it has -- you almost certainly would otherwise miss. It will also help you understand the significance of the laws you find.
For international law, secondary sources will help you identify the legal framework for an issue, learn the terminology, and discover which documents you need to look for.
1. Identify what you need
2. Understand the structure of the foreign legal system
3. Identify the sources of law for the country
4. Use a library-authored legal research guide
5. Use a secondary source
Credit: Slightly adapted from Georgetown Law Library's Foreign and Comparative Law research guide. Source: https://guides.ll.georgetown.edu/c.php?g=362128&p=2445998