The importance of having an organizing system for your sources cannot be overstated. It will save you time and tears in the long run, and you're best off picking a system early in the process and sticking with it.
There are three systems that the library can help you with: Zotero, RefWorks & EndNote. These tools are called citation management software.
This is what they do:
Plus links to other types of software (Zotero, EndNote, etc.)