I have read (somewhere) that the single most important role of a leader is to create consensus. It is not your job as a leader, ideally, to make the decision, but to facilitate your team members coming to a consensus on the best decision. Sometimes, of course, you will have to make a decision, and that is where having a strong background in the area helps out, but that is when a consensus could not be reached or some other constraint got in the way of your team coming to the best conclusion themselves.

Also a Steve Jobs quote I always found informative on leadership, “You don’t hire smart people to tell them what to do; you hire smart people so that they can tell you what to do.”