While I've read both Case in Point and Case Interview Secrets and believe that both provide useful tips for preparing for case interviews, I'm a strong subscriber to Victor Cheng's philosophy laid out in "Secrets." I believe that people prepare and learn in different ways, but find the "Secrets" philosophy to be the most sound and easy to coach.
I believe that all case problems can be structured into two key frameworks (Profitability Analysis and Business Situation Frameworks). I aim to deploy one of these two frameworks against every case (understanding that critical thinking and modification of these frameworks may be necessary).
I think it's also important to note the subtle differences between interviewee-led (e.g. Bain) and interviewer-led (e.g. McKinsey) cases when thinking about frameworks and strategies. Using an analytically rigorous framework like the Profitability Analysis framework is an even more useful ally in solving interviewee-led cases.
My case approach is to run the case with the candidate and (as I did when I was an intervieewer at a Big 3 consulting firm) always try to find ways to make the interviewee successful. Once the case is over I will note the ways that I see areas for improvement, based on my knowledge of the ways that interviewers appraoch grading cases. I will also note things that they might have gotten away with this time, but that they might not get so lucky if the case were to have bended in a different direction.