BHP Billiton standardized on the TopGrading (http://topgrading.com) methodology for hiring. Basically, be prepared to answer variations of the same 5 questions about your last 4-5 jobs or companies you worked for. 1) What were you hired to do? 2) What were your high points? 3) What were your low points? 4) What would your boss/peers say about your performance? 5) Why did you leave?