Hi,
Great question.
First, about the portfolio, I am a fan of 'ideas and concepts'. I've seen lots of portfolios containing brilliant technique and cool pictures. In the end, that's all they were and I was left wanting more.
But displaying a range of technique as it is applied to smart ideas and concepts take the portfolio a step further and make it memorable.
Not sure how to answer your 'light' question, however with regards to actual lighting in a scene, there's no better source than cinema to use as reference. Also paying attention to 'Pixar's' movies are a good way to study lighting I've found.
Where should someone begin? Firstly, they need to have a unique, marketable perspective (this is not always easy or possible). Secondly, the dedication and intelligence to make there own way in art. Thirdly, they need to do any task, no matter how trivial. If I had a team, that is what I would tell them.