It is worth keeping a good record of the searching that you do and the results that you find when using online resources.
You will find that many of the databases you use (such as the MLA Bibliography and LION) will let you save searches and email results to yourself. Check the help section of any resource you use to see what might be possible.
The Internet, of course, also has some excellent free resources. But how can you evaluate whether or not the resources you find when you search independently are good enough for your studies?
Internet for English is an excellent self-guided online tutorial, especially for students of English, or, take a look at The Internet Detective
There are several useful guides to evaluating information on the Internet produced by other universities, take a look at this guide from John Hopkins University: Evaluating information found on the Internet