I'd run for president in the US, get the votes, then lead America to a time of poorness and despair...Oh, wait, that's been done.
No, but seriously, I'd be nice for a decade, build up the confidence and gain the trust of everyone so they'll do me favors. I'll trick them into doing devious things that will make me be able to create an empire, take over the planet, and give villains the right to do anything. Then, when all that is done, I will flee from the destroyed planet before I die, bring a few evil friends, and move to my secret base on the moon, with TV and all video games, and a parallel universe portal, so I can get DNF. Then I'll take over that universe, and the next one, and on and on, until I finally get what I want... A cake that isn't a lie!