Everyone at BCG was very friendly and helpful throughout the process. Getting to the interview stage depended primarily on your resume and ability to make a connection with a representative at the information sessions. The info session is the first step--don't miss it. The interview itself was two case interviews with two different BCG people. I would advise focusing on sharpening your business vocabulary, reading business newspapers, and practicing some cases (don't go overboard here). The cases are not all that matters. You also need to interact well with the interviewer and demonstrate your understanding of the business world.