David, the political strategist and mastermind

Though David may not at first have seemed destined for Kingship, he was the man! He has been described as faithful, courageous, smart, sincere and competent. He was a good warrior and he had a presence that was infectious. He had it all and people loved him. But like all humans, he made some questionable choices. The question is, did he operate out of self-interest or did he work for the common good? What can we learn from his leadership?