In general, for all formats:
Is the source scholarly? If so, then many of the questions regarding accuracy or reliability are embedded in the nature of a scholarly source.
Is the writing clear and free of grammatical and typographical errors?
Do the facts in other sources support the facts presented in this source? If things don't match up, you will need to determine which is the better source.
Are the sources for statistics and facts documented so you can verify them in another source? (It’s a good idea to do this).
Are quotations attributed to named people? Be sure to track down the authority of those people as well.
For books:
What evidence of research is provided? Look for references or a bibliography / works cited, endnotes or footnotes.
Have book reviews indicated that the book offers accurate, reliable information?
For periodical articles:
What evidence of research is provided? Look for references or a bibliography / works cited, endnotes or footnotes.
Is there evidence of bias or propaganda? (See the Purpose guide for more details)
Did the article undergo peer review?
For websites:
What other sites have links back to this site? Using Google, type in “link:” immediately followed by the website address.
Is the website well-organized and easy to navigate?
What are the author(s) research methods?