This HBR article from 1966 is the first I have ever seen to have really analysed the psychology and processes behind the purchase of Professional Services. What exactly is the client looking for?

The piece that particularly interested me was around "determining the ability of the professional service firm to deal with a problem."

The two approaches are extrinsic and intrinsic.  

The Extrinsic approach (& I paraphrase) is - Our Firm is good because we have a unique approach, we all went to Harvard/ Cambridge and Apple/ Google used us - and look at them now!

The Intrinsic approach, by contrast, is to engage with the issues with the client and to get them to a point that they can purchase your services with a high degree of confidence.

The Intrinsic approach, a-hem, is hugely benefited by using highly relevant, timely, expert-led content to move your firm to a well-justified position of trust in your clients eyes.   

See below for the authors view on the merits of the two approaches...