3 Things to keep in mind for case interview prep: Fall Interview Season is around the corner

General suggestions on interview prep:
My thought is, there is no over prep. Prep a lot and work hard. More tactically, here are some suggestions:
Strategy and Case book: there are a lot of case books out there, and different ones can be helpful for different people. Some of this is trial and error. But, what's most important, is that you find a case book that helps you learn the strategy and approach to tackling a case. It's like studying for the SAT or GMAT. At the end of the day, there are many test prep companies and many ways to tackle the test. It really matters which one you resonate with. So try to figure this out as soon as you can.

Practice: once you learn the basic dance of the case, and you have your strategy and approach, it's important to know what materials to use to practice and how to practice. For materials, there are a lot of good PDF's online from MBA programs / business schools. For example, you can simply type in name of the business school and "Case Book: and you'll find many PDF's online. These will usually be older versions, but the cases are still good! These tend to have great practice cases, and if you get multiple books, you can easily find hundreds of practice cases you can work on.

Self practice vs. live case. My opinion is you have to do both. If you play a sport or chess or any instrument, you know that there are competitions or performances where you're performing and testing/showing your skill, and then there is practice. Practice is usually much more focused on strengths you're trying to build further or weaknesses you're trying to overcome. Casing is similar. Find time to 'perform' and do live cases with someone. But also figure out what you need to work on, and find time by yourself or with drills that can help you work on these things. E.g., if you need to get better at calculating percentages, doing practice percentage math drills is far more effective than doing 10 more cases. But at the end of the day, you have to do both.