What are the study habits of top students at Harvard University?

From what I can recall, the students who had particularly high GPAs followed these types of habits:

• Minimizing distractions — working out of a library or otherwise quiet space was important, especially during lengthy reading of books or writing essays.
• Collaborating on problem sets — I remember a bunch of people working on problem sets together in the Science Center or Littauer. Not sure how this would apply to Humanities classes, but collaboration and accountability to each other is an effective technique.
• Going to sections — even students who missed lectures would make sure to go to sections where TA’s and TF’s would provide additional, more easily digestible insights about the lectures and sometimes help with particular problem sets or essays.

To be clear, I personally don’t value optimising for GPA, but this was a positive question, not a normative question. If you’re optimizing for learning, I would make sure to go to the actual lectures and, most importantly, put yourself in as many open ended discussions with smart people as possible.