I would try to unite the world in a common goal: Planetary Excavation and Reformation. Anyone who opposes me I will offer them to join me. Any third world countries I will try to make sprawling utopias. I would use as much resources as I can to invent new resources, and I would try to solve any crisis that arose. After terraforming our system, I would work on technology that would propel us to the farthest stars. Still, I would solve any problems that arose back on the home planet, and I would assure that each other planet would be equally independent but received their own share of wealth. And with our focus on progressing science, no life form from another system would dare destroy us, as we would have too much resources to offer to them. I would make alliances with other systems, bring them under one, fair and equal rule, and I would slowly spread equality and justice throughout the farthest reaches of our galaxy. And once our galaxy is united, we start on another one.
Pretty evil idea, huh?