It is important to remember that using a checklist will never let you determine with certainty whether or not a use is fair. It can, however, help you organize and, importantly, document your thinking. It's a great idea to use and print a fair use checklist whenever you are dealing with a tricky fair use situation. Take the time to document your thinking in case of a future challenge!
This checklist allows you to check off the factors at play in your analysis, as well as add text that explains your thinking, and then emails you your results. This is a great thing to keep for your records.
Columbia University provides excellent context for why and how to use a checklist and provides a checklist for your use.
The Center for Media and Social Impact has worked with a wide variety of user communities to document the best practices for applying fair use in those communities.