Remember, many online resources now provide citations formatted for your Works Cited or References page. Look for them when using databases and online encyclopedias.
Don't forget to include in-text citations too.
Zotero is "a free, easy-to-use Firefox extension to help you collect, manage, cite, and share your research sources. It lives right where you do your work—in the web browser itself."
Stony Brook University has a site license for EndNote, a bibliographic tool which enables users to quickly organize references while automatically building bibliographic documentation.
The library provides free EndNote workshops each semester. Check the library homepage for upcoming dates.