Didion on Investigative Journalism
Joan Didion, in her preface to Slouching Towards Bethlehem, her first collection of essays (highly recommended).
My only advantage as a reporter is that I am so physically small, so tempermentally unobtrusive, and so neurotically inarticulate that people tend to forget that my presence runs counter to their best interests. And it always does. That is one last thing to remember: writers are always selling somebody out.