I think the quote that is most relevant to leadership today is "It is not essential that a Prince have all good qualities, but it is most essential that he should seem to have them." Leaders today must be elected in to office in most nations, so they have to earn the votes of the people. To do this they must seem like they are good people and good leaders. The people aren't going to vote for someone who seems like they are a liar and a bad person. The most important thing for leaders is to seem good, they need to seem like they are honest and fair and that they have good morals. Even if the leader isn't this way, they need to be able to convince everyone that they are. The voters want someone who they can trust in office to do the right thing.
I think that the quote "The ends justify the means." is bad advice for leaders today. In todays world everything that a ruler does is being closely watched and scrutinized. People are watching to see that you do the right thing and if you don't you will quickly lose your position. The ends definitly won't justify the means if what you do is not moral in the eyes of the people.
I think that the quote "Before all else, be armed." would have been helpful for the Incas. The Incas let their guard down thinking that they didn't need their weapons and this lead to their downfall. If they had had their weapons the story of Pizarro and the Incas might have been different. The Incan leader did not believe that being armed was a top priority and this was his mistake. Being armed should have been the most important thing to him to keep him and his people safe, but it wasn't and the Incas paid for it.
