I was once a PrepLounge user...
I have trained with 100+ case interviews, before taking the interview and claiming on offer at BCG. After that I spend 3 years in the Group and was part of the recruiting team as well. I will prepare you beyond "just" solving a case. Therefore I'd like split our time in 1/3 Case, 1/3 Bag of tricks, and 1/3 Q&A + Feedback.
So, I will teach you some tricks, make sure you avoid some pitfalls and make you aware of what the consultant (don't think of them as an interviewer) is looking for. Here is my first trick for you–that one is free:
The seating is important. You are likely to be the first in the interview room. Depending on whether you are right or left-handed, take a corner seat. Thus you are "open" to your interviewer, so they can read and follow your actions better (and believe me, they will).
Looking forward to preparing you!