I tell my students to ask themselves 'why should I believe this source'?
They then start to explain why the author is trustworthy, or not, whether or not the content is the same or similar to other sources, which side the author is and how that would be impacting what they were saying, the problems with it being either primary or secondary (primary - one person's opinion only while secondary - has the advantage of reading numerous accounts and less likely to have the bias of the day), it is propanda, why did the writer write it e.g. Lloyd-George's scathing attacks on Haig have to be tempered with the fact that he wanted to make himself look better in his memoirs and reflects his own class bias.
I don't have a checklist as such - and find, as someone who has marked this, that often checklists end up being rather trite answers rather than really dealing with the issues.
If you have a source you would like to analyse send my a PM and I will look at it for you.