First, I spent over 20 years teaching Gospel Doctrine weekly. To prepare for a class I would read the assigned scriptures on Sunday evening. Beginning Monday I would research in commentaries what others had said about the passages in the assigned lesson. Then before going to bed I would re-read the scriptures for the next lesson.
I would continue this process daily until Thursday. Beginning Thursday I would start to outline what I intended to cover in the lesson on Sunday.
Throughout the week I would listen to the relevant scriptures for the next lesson on tape/CD whenever I was in my car. So on the way to and from work I would listen and re-listen to the scriptures.
On Saturday I would pray then put a final lesson plan together. It took about 10 hours a week for me to prepare a 50 minute lesson.
In all the time I taught I never repeated a lesson. I tried to go deeper and deeper into the meaning of the material every time I taught it.
Today with that background I read books and scriptures daily. However, I take what I learn back into my scriptures and add cross-references or margin notes to make scriptural passages more meaningful for me. My scriptures have very little underlining and no coloring, but there are many notes and cross-references in them.
I try to tie any new concept I learn, no matter the source, back into the scriptures. Lately I have also taken to using an electronic version of the scriptures to help locate material or passages which relate to a topic.