Online stuff isn't going to be very good. Try a Half Price Books if you're in the U.S., and buy a textbook; far more detail and more comprehensive. Web pages are simplistic and not nearly as informative. they should be cheap, and even current in many places, but the basics don't change that fast.
Search your areas of interests on Google Scholar and its search results show some books and articles that are available for free online. Look for PDF links on the right side of the page for free articles that are open for everyone and some books in search results are also fully accessible from Google Books. http://scholar.google.com/ Van Evera, Stephen. Guide to methods for students of political science. Cornell University Press, 1997. http://books.google.com/books?hl=en&lr=&id=V3pSlccSRDAC&oi=fnd&pg=PA1&dq=political+science&ots=5ixKwZ6I0A&sig=WZTVKeX93ofiD0djf0LCh28ySjY
