Personally, I think working for direct clients has the biggest potential impact on earnings for freelance translators, and her point about being a businessperson/translator is spot on. Direct clients certainly make the world of difference for newly established and mid-career translators as they work towards a high degree of specialisation (very likely in a completely unrelated field) and try not to starve in the process. Finding these direct clients is of course another story (and one Chris Durban is eminently able to tell, in my opinion).
On another note, I do love posts like Corinne’s that acknowledge the diversity of a group, weigh up a couple of factors from a range of sources, add some personal insights and then draw something useful from it all. Excellent stuff!