Recommended minimum content for IPTC Core metadata

[Chris of Arabia]

Whilst far from being professional, I'd like to apply a sensible range of IPTC core metadata to my images using Adobe Bridge as I'm processing them out of the camera (I'm assuming Lightroom does something similar). Could I ask those who have more of a vested interest in protecting their images what metadata they consider to be the minimum worth applying?

To me, 'creator', 'copyright notice' and 'rights usage terms' seem the most obvious candidates, what else would you make use of, and particularly in the case of copyright and rights, what do you put in them?