One of the lessons that Guy Kawasaki learned from Steve Jobs, which really rings true to me:
"Experts are clueless. Experts -- journalists, analysts, consultants, bankers, and gurus can't do so they advise.
They can tell you what is wrong with your product, but they cannot make a great one.
They can tell you how to sell something, but they cannot sell it themselves. They can tell you how to create great teams, but they only manage a secretary.
For example, the experts told us that the two biggest shortcomings of Macintosh in the mid 1980s was the lack of a daisy-wheel printer driver and Lotus 1-2-3; another advice gem from the experts was to buy Compaq. Hear what experts say, but donât always listen to them." (from How To Change The World)