ISC2 has study groups for the CC although I do not have any experience with them. The answer on preparation is that it depends on the individual. We all learn differently. For some the self-study training will be enough. Some do well with flashcards which ISC2 has at no cost; I am not one of those. I did buy the eTextbook just to review it for others. I am not sure that will help a lot. The most important thing is to know the exam objectives (ISC2 calls it an exam outline). They will also help you identify any gaps in your knowledge. I do know people who also took courses from Luke and Thor; others say that they have read one of the books out on it to prepare. So you really need to identify to yourself how you study and learn best and concentrate on those methods of study. Best wishes.
