Diagram LR?

I am currently PTing at ~158 and I would like to get up to high 160s (goal score is 169). I am getting about -5 to -7 for each LR section, so obviously this is a place I can improve. I have the LR binder.

For people getting -2 or -3 on LR what did you study? Did you diagram LR questions? Did this significantly slow you down?

Also, outside of PTs, where can I get LRs to work on with decent explanations as to why one answer is picked over another.