LionSearch or Google Scholar is a good place to start but it cross searches a lot of different disciplines from the arts to zoology. At the same time, it doesn't cross search all the databases owned by the University Libraries and, in fact, misses some crucial databases in the social sciences, including Psych Info and CIAO (International relations).
To use a fishing analogy. When you fish in the ocean there are lots of different kinds of fish. You will catch something. However, if you fish in a pond that has been stocked with the type of fish you want to catch, you greatly increase the chance you will get what you want for dinner.
Use a subject specific database to focus your search on the exact type of information you need. Fish for information in that smaller pond! LionSearch will even offer suggestions as to which database might be most useful. My top suggestions for political science literature are below.
Watch this quick video for tips on using a subject specific database effectivel