The best way to try and succeed in doing this would be to form friendly allegiances with as many countries as possible so you could have an army appoint yourself as ruler of your country and take command quickly be sure to at least be kind to your opponents in helping you take over or they may start to question themselves following you and may possibly k!ll you unless you were to show no mercy with them and harsh commands to show who is boss and of course you have got to have weapons, but other than all that you should be on your way to conquering the world in 15 days I believe LOL :)
Confidence. Walk into the White House, schedule a press conference about your claim to the throne, then have a representative sent permanently to the headquarters of every country in the World. Hold another press conference and announced the New World Order. Then announce your role as a subject/apprentice to me.