Barrington offers a thin guide to the business of consulting, and to my eye she seems more concerned with the financial side of things: structuring a start-up consulting firm so any implosions are contained, making sure that clients understand the value that you're delivering, and that your accounting is reasonable. There's less on developing a market, or going from zero to something. Not sure it's worth what I paid for it, but free advice is often worth about the same. A solid reference, if nothing else.