General Interview Thank You Email I Have A Job Interview With One Of The Largest Advertising Agencies Soon! What Should I Prepare/know/expect?

I have a job interview with one of the largest advertising agencies soon! What should I prepare/know/expect? - general interview thank you email

I asked a graduate scheme for the post of account executive / planner. I want to do really, and the competition is tough. Anyone who maybe in the industry? Or the General Council before the interview? Thank you very much!