How do you get respect as a ruler? By winning wars.
Look at the King of Spain. He was once just a wimp, but now he's the most famous king in Europe.
War not your thing? Too bad. But you can also handle your nation's domestic affairs awesomely, and that will work, too.
Also, you need to be a genuine friend and enemy. What Machiavelli means by that is, if two of your neighbors are fighting, you have to take sides. If you don't, then the winner will come after you and the loser won't help you at all. If win, you get spoils; if you lose, you can plot your revenge together.
A ruler should also give prizes to overachievers, lower taxes, promote small businesses, and give people parties.
Also, show up from time to time. That way, everyone will remember how awesome and yet authoritative you are. Yep. This part seems just silly to us, like Machiavelli had to fill up the end of the chapter to meet his word count. (Hint: next time, Niccolò, just change the character spacing.)