Question special

What a great discussion thus far! We've already heard about individuals' key tips for success, including starting early and planning ahead, making a flexible but deliberate schedule, using practice tests, and cultivating an optimistic and learning-focused mindset. We also recognize however that many of you are using a diversity of paper-, online-, and classroom-based resources and would love to get more into the nuts and bolts of these. Which study resources do you swear by for the various exams (in medical school, residency, and beyond)? Have particular resources been more or less helpful? If you have enrolled in a study course or find that approach (tutoring/classes) helpful, please comment here too.

(PS> A related question: what makes a particular study resource a high quality or valuable study resource for students? Please try to comment on why you found that resource useful if you can.)