I am looking to improve the speed/minimize the time it takes me to learn and retrieve information.

I am searching for the biggest differentiators, within someone's control, that determine the amount of time it will take someone to be able to recall what they have learned at a later date. Put another way, if you had 100 hours to teach someone a subject they were highly motivated to learn, how would you get the most out of those 100 hours?

Can anyone provide direction regarding classic texts on the subject or research summaries? I am looking for immediate steps I can take to make my learning more efficient. Knowing the why is a secondary priority to knowing the how.

Thank you for your help.