Fred Wilson venture capitalist and Co-Founder Union Square Ventures
“The Board of Directors is the [company’s governing body]. All major decisions [require Board ratification, including approval to sell, hire or fire a CEO, make major acquisitions and do major financings, including an IPO].” All strategically significant issues need Board involvement and support.
“[The] Board should not run a company [but ensure] the right team is at the helm . [Boards] must always act in the best interests of the company and its major stakeholders:  employees, customers, shareholders,  debtholders, [etc.]  The company works for the market  and the Board and the management team work for the company.”
Often, as director a right answer isn’t straightforward. “There are no formulas [nor “right answer”]. Only time will tell if the right decision was made [which can be debatable].”
A good board is engaged, debates openly and honestly and tries reaching consensus. The Chairman should drive the Board.
CEOs shouldn’t manage the Board. “A great Board manages itself,  treats the CEO as a peer, [and considers the CEO's opinion,][but isn’t] a rubber stamp. [It] pushes the CEO and the company to make the most of [presented opportunities and asks necessary hard questions].
 [Boards] should evolve [with members changing occasionally, and some but not too much churn is good.]  Boards should always be looking for new blood.” Fred Wilson, The Board Of Directors: Role and Responsibilities, Mar 5 2012; http://www.avc.com/a_vc/2012/03/the-board-of-directors-role-and-responsibilities.html