Commissario
By being professional and very deliberately keeping the news part of the organisation largely separate to the rest of it in terms of management etc (IIRC even very senior BBC staff can't directly influence news by design), and making it clear that standards are to be maintained by the staff on the news side.I always find it weird when BBC is doing news articles on itself, like how do you remain impartial ?
There have been various stories in the past about how people outside of the news management have tried to influence the news side and been told to take a hike/talk to someone higher up.
It's one of the biggest differences between the BBC and say most of the news papers, the BBC will report on itself even when it makes them look bad, most of the papers won't even report on major stories about themselves if it puts them in a bad light.
IE IIRC the BBC reported about Basher and the Diana papers, but most of the news papers barely mentioned the fuss about the phone hacking etc when they were very publicly being taken to court over it.