Here's a real-life example of engaging/evaluating resources from Tyndale's manager, Helen Howell:
As I listened to the people I had identified as the most important authorities on my topic, a couple of different arguments came into focus. The pre-Tolkien scholars had been divided into two main camps: those who thought the historical digressions intruded on the important monster bits, and those who thought the monster narrative intruded on the important historical material. Both were looting the poem for what they thought was the truly valuable stuff.
Tolkien (all hail!) single-handedly revolutionized the approach to the poem by suggesting very sensibly that it should be approached...as a poem. As a hale and hearty and complex work of art in and of itself, and not as a chest to be raided for historical or mythological material (though of course both of those things were present). The scholars who followed him were as a result much more unified in their approach to the work, if not in their conclusions about it.
I was listening to books by Klaeber, Tolkien, Brodeur, and Bonjour in particular, and I sticky-noted the dickens out of those four books, taking research notes as I went along of how each author fit into the big picture and how his material related to my questions. Some ideas that popped up along the way had to be discarded based on their scholarship (not every tiny digression fit into the pattern, however badly I wanted it to), and others had to be kept on a provisional basis. (The connection between Scyld and Grendel, although arguable, was definitely more tenuous than the one between Unferth and Grendel, despite my best efforts).
Klaeber and Tolkien gave me some great background information, which gave me a foundation to start with. Bonjour and Brodeur had some fascinating and detailed arguments about the interpretation of specific digressions, which usually served as support for my own argument--although a few of their observations provided some complications I had to address. They forced me back to the text and made me wrestle with it.
This made me realize my final question, which I answered in my thesis statement: If the digressions foreshadow the monsters (which they do, as I established in the body of my paper), why did the poem end on a long digression? Was it hinting at a fourth and final monster? And if so, what was it?
Sorting through these materials took time, effort, and concentrated thought, but by the time the books were stickied and my notes organized, I was already almost done. I knew what the question was that I wanted to answer, I knew who had been talking about the issue already, and I knew how all their arguments fit together. All that remained was to assemble the material coherently around the structure of my own argument.