Learning How To Learn ( https://www.coursera.org/learn/learning-how-to-learn ) and Barbara Oakley's book A Mind For Numbers . Completely changed my approach to studying and learning, and my academic efforts after taking it were tremendously better than before. Also related: highly recommend Anki. It feels like magic when the spaced repetition works!
What would you say are your biggest take-aways from that course?
* Diffuse mode vs. focus mode. After focusing hard on a problem, letting your brain wander can do wonders for coming up with insights and ideas. The classic example is coming up with something in the shower after working on it throughout the day. I've focused much more on giving myself some of the non-focused time after focused periods (ex. going for a walk/run/swim, taking a nap or shower, etc). I've started doing this more for work, as well.
* How memory works (short-term vs. long-term) and along those lines, spaced repetition. All through undergrad I would cram, but spacing it out (with the help of Anki for flashcard-focused topics) really does wonders.
* Importance of actively quizzing yourself, practice, and working through problems as you're learning something.