I've started a commonplace book.
I first heard about these in The Well Educated Mind by Susan Wise Bauer.
Apparently, all the cool kids were doing it back in colonial times (including Thomas Jefferson.)
A commonplace book is like a journal. Chances are you already have one.
It's a blank book where readers write down quotes, pieces of poetry or prose, etc.
So far, in mine, I've got quotes from books, notes on books, essays, and Google searches.
I've got definitions, Bible verses, etc.
I also write down my questions as they come to mind, so that I won't forget to ask them again.
I am beginning to think the right questions can be just as important as answers anyway.