Rupert, thanks for the ego boost, but I definitely won't claim any expertise - just happy to help.
As for lighting stl, to me it's all about getting the balance of your lights right. If all lights (two main lights for the subject and one for the background) are all of the same intensity, then there will be a very evenly distributed exposure, which lights everything up OK, but leaves no room for rendering texture and creating contrast, which does help in portraiture.
My suggestion would be to experiment with your lights - firstly by trying to reduce your background lights to half the intensity, snooting it (to create more of a vignetting effect on the background), then either increasing one main light or decreasing the other with perhaps a change of angle to the reduced light to create more of a fill/kick light effect rather than another main light. For examples of how this works the maestro on this forum is devisor - check out his portraiture and see how his images are produced.