Keeping track of your sources doesn't have to be a burden. There are tons of free citation management programs available. These let you download, print, and send your citations as you go. Just be sure the program you are using has the citation format you need.
If you prefer physical sources for research, a low-tech and cost-effective method is using notecards. Use one card per source and write down all the bibliographic information. You can even add notes on the rest of the card about the source. The Citation Resource Guide below shows you how to write citations in AMA, APA, and MLA formats.
Zotero is a free citation management software that stores and generates accurate citations and bibliographies. Available for Mac, Windows, and Linux.
EndNote is the industry standard software tool for publishing and managing bibliographies, citations and references on the Windows and Macintosh desktop. This software is not free, but they do offer a free version called EndNote Basic.
Mendeley is a free reference manager and an academic social network. Available for Windows, Mac and Linux.
Citation Machine™ helps students and professionals properly credit the information that they use. This is a website that can be used to create citations in a variety of styles. It is free to use, but does have ads.