1. Trying to "put more effort" into artifacts (e.g. note taking) while learning something the first time is counterproductive. Write something lightweight and put your focus on paying attention.
2. Do one intensive review session while you still remember the content. Either teach someone else or write a document that could teach someone else. It's an ineffective use of time to do that more than once, for later review of the material just skim what you wrote on your first review.
3. Everyone who offers advice is just telling you their life story, dressed up as a simple directive. "Work harder" often means they wished they worked harder in some part of their life. Treat it like any other life story: learn the lessons they did, but don't let it become baggage that you irrationally follow.
Back on topic of Polya's How to Solve It, I took a no-credit uni course where the professor taught in Socratic style that expected us to (loosely) follow Polya's process. It was a great experience, and I've always been fond of Polya's steps because of it.
