I hope this note will help any applicants for cabin crew positions.
The interviews in which I excelled (and got the job), were the ones in which I was level headed, friendly and calm. My failed attempts were the ones in which I tried too hard (and probably came across as desperate).
Oh, and ignore anyone who tells you to smile a lot during the interview. Smiling for no apparent reason makes people look silly at best and deranged at worst. You're supposed to create the impression that you will be able to take care of people's safety, comfort, etc.