Very professional from the beginning till the end. Both HR team and interviewers themselves made the whole hiring process enjoyable. Didn't regret applying at all.
1) CV and CL. Make it polished, professional, yet don't try to sound over-excited to join Bain. Be realistic about your expectations and your motivation to work in big consulting.
2) Written Case. Time management and good math is the key. My advice: subscribe to the Bain social media resources, they give relevant info about the hiring process and what to expect (case examples). It will help you a lot.
3) First round interviews. You have to be prepared. If you are applying to BIG3, you already know about Case in Point, LOMS, etc. So make sure you use all of these. Go to the mock interviews, practice with your friends, join the case clubs. Just remember, you won't go any further unless you'll do your homework. Don't neglect the fit part.
I was not prepared properly and didn't make it to the second round.