Dictionaries with an international law focus can be an excellent place to start if you are faced with unfamiliar legal terms.
Encyclopedias can be an excellent place to begin your research. They will give you a brief overview of a topic and often will cite to primary resources.
Another excellent starting point if the information in this guide is too current is to look at more advanced research guides that have been published on both public international law generally and on specific topics. One particularly good guide is ASIL's Electronic Resource Guide (ERG), which provides information and links to primary documents for a variety of important international law topics.
Additionally, there are a few searchable and browseable repositories of guides dealing with international legal research available on-line.
EISIL is a free, online searcheable database of international law information that links to authentic primary materials and authoritative web sites. Designed by the American Society of International Law, it searches more with more depth than Google and is an excellent place to search for online materials.