I read a blog post written by her once - I think an old one from The Tig - where she tells of advice from her father about 'knowing where (her) light comes from' or words to that effect.
It's very clear in every public appearance that she is acutely aware of where the camera is and is angling towards it.
This is in contrast to the advice generally given to Royals (as exemplified by Prince Philip) so was probably another way she struggled to fit in to life as a working royal.