Start by finding secondary sources, such as books and journal articles, these will give you context about international material, foreign legal systems, and the primary sources in different jurisdictions.
Use GlobaLex to guide to through the main principles of different legal systems and this site will also guide you to the primary sources of law.
Use the ICLR Database, this will give you access to Queen/Kings bench reports and other UK Reports.
There are several databases that you can use to search for international citations.
You can start searching for many international titles directly through Library Search and Google Scholar. See below for law specific databases that have international content:
