How do you keep track of material?

I am a Christian writer trying to get into writing for magazines, so my focus is non-fiction. (This is also my first post on here so -- Hi, everybody!) I am also a notorious note-taker. Anything that I consider even remotely significant I copy off and store away for future reference, which means I read non-fiction with a tablet and pen beside me. At times I regret not reading faster and getting to more books in a year so I decide not to take notes. But then I inevitably find myself leafing through every page of the book to relocate some specific portion. Some books that I do not intend to loan and are of even greater significance to me have markings and notations throughout.

Now I come from a big family which has taught me just how different we all are. So what I’d be interested in hearing is how each of you keep track of material you want to keep for future reference. Do you take notes while reading or not? What are your categorizing methods in general?