I'm not commenting to anyone who has already spoken, but to those newly navigating the question. No one has mentioned, probably because of familiarity, to grade sources on a curve. Some sources are indexed with a name and date only. I don't like using those, if I have options, even if everything seems to match. I've seen to many cases of wrongly indexed sources.
Some FAG sources have photos of the gravestone and include links to known family members nearby, also with photos. It's the same with census or other microfiche, I like to see it myself. My confidence in the accuracy of any source increases, depending on what is presented.
Census takers and other recorders could also make mistakes. I have found those records accidentally by looking at microfiche and noticing the very mis-spelled family name on the same page, with all given names and ages matching. If I hadn't been viewing the fiche, I never would have found that record.
I recently found an online archive of parrish records dating back to the 1600's. When I clicked the link to look at the original, it was a typed index in book form. Because some names and dates were not aligning, I suggested contacting the parrish to get a review the original.
I really love finding lost puzzle pieces. Sometimes it takes a spotlight the size of a retina-wrecker to get at the dark corners and find them all. :)
Question everything. It's like building a house. Consider if that brick wall could have been one built accidentally.
uugghh... sorry for the "edits" I'm trying to get fonts big enough for me to see.