Follow the same steps as you would for any research problem. Although there may be curveballs for international, comparative, and foreign law topics, your goal is still the same.
Similar to doing U.S. legal research, it is important to start with secondary legal sources, in order to find primary authority, the authoritative law source. Secondary sources are used to evaluate findings, analyze, and draw conclusions. The Internet is an important source and should be used carefully. The best web sites have authoritative information, are consistent, and are constantly updated. If you are unsure about the authenticity of a website, check with a reference librarian or just don't use it. Print materials and electronic formats of Lexis Advance, WestlawNext, and Bloomberg are also basic sources, all of which must be used to do competent, thorough research.
It is very tempting to use Google, but know that there is a resource that may very likely have this work done for you! That will tell you exactly where to go, both electronic and print, for many subjects in many countries.
George Wash. Int’l Law Review, Guide to International Legal Research (2015). Available on Lexis Advance - start typing the title into the main search bar; also on the second floor of the library by the reference desk: KZ 1234 .G85 (ref).
American Society of International Law - Electronic Resource Guide. Constantly updated. Online resources for specific areas of international law, such as: international piracy, the European Union, international organizations, etc.
You can use Google - it is your friend! But be aware that it has limits. If you are looking for a specific document that is relatively frequently utilized, it is highly likely you will find it (and even from a reputable source). If you are looking for secondary sources, they will be more difficult to find on Google - partially because there are A LOT of them, but also because many are only available from subscription websites. Government documents can usually be found in this way, but it may take more digging on a government website. The ability to access government information also depends on the transparency and government publication laws of a particular state.
Journal indexes allow you to easily search by subject matter, and then provide a list of related articles.
There is a large collection of print journals on the third floor of the Library. You can search for journals in the Library Catalog by titles, subject areas, and key words.
The use of statistics can be valuable and meaningful to the position you are researching and writing about, but remember the saying long attributed to Benjamin Disraeli: “There are three kinds of lies— lies, damned lies, and statistics.” Make sure you use a reputable source for identifying statistics, and use them appropriately and accurately. Anything less will harm your reputation and may hurt your grade or, worse yet, your client’s case.
Billie Jo Kauffman. "Finding and Using Statistics in Legal Research and Writing" Perspectives: Teaching Legal Research & Writing Vol. 14 Iss. 3 (2006) Available at: http://works.bepress.com/billie_kaufman/2/