And while I've tackled research before, I haven't done an entire column on it. (And for those of you who aren't reading Tyler's column over at Comic Related, shame on you!) I've mentioned it here and there, though.
I don't know if there's enough material to actually do a column on researching folklore. (I like that better than "fictional concepts.") Well, there is, but it would take someone more intelligent than myself to do it justice and not bore people. And, really, despite what some of you may think, I'm not that smart.
Anyway, the general places to start, I would think, are OLD books. Start as old as you can (I'm talking the 50s and 60s, when books like these were starting to become more accessible), and then progressively move forward in order to get a sense of what has and hasn't changed, what's been elucidated upon, and what's been abandoned. I think that would be a great way to start, because you get a nice overview (chronologically, at that!) of how views on the various subjects have changed.
Now, when it comes to folklore, there are precious few facts, and those are often contradictory. There are also regional discrepancies, and some "facts" change as soon as you cross a country border. One vampire trait may be different than another vampire trait in two different towns, where only a small river acts as a border between them. Cross that river, and you're not only in a different town, but a different country. This makes researching folklore difficult.
When it comes to facts for folklore, you have to remember that, even when people were keeping records and were "putting down" vampires, a lot of their "evidence" wouldn't stand up to our 21st century methods. (Then again, the same thing can be said about the use of magic(k).)
Difficulties abound, but as the X-Files told us every week for years, The Truth Is Out There.