Enough is enough... or is it?

For some reason I can't set foot in the New York Public Library without thinking about Ghostbusters -- but that's aside from the point.
I was back at my favorite haunt last night, and even though the visit was unplanned, it was productive. In fact, I found and photocopied material from three more books detailing Yugoslav history. It took a couple of hours to find and copy everything I wanted, and as I look at the growing stack of research material on my desk I cringe when I think about how many trees were sacrificed for the cause.
To be honest, I'm starting to feel more than a little overwhelmed by this research project. The subject is dense, and it seems the more I find, the more questions I have and the more confused I get.
So I think it's time to stop gathering material and start sifting through what I've already found. I suppose I'll start making outlines and timelines and take it from there. In any case, the bottom line is, that until I not only understand the history of my father's homeland, but feel confident enough to write about it with some authority, I simply can't begin to think about character or plot development.
What about you? How do you go about doing research for your own books. Do you take a methodical approach or fly be the seat of your pants?
I'm eager to hear what you think.
Until next time, "That's life..."