Start the Dyson Swarm. Become a K2 civilisation. Dismantle Murcury for material, and preserve Earth for posterity, if not strip it for parts.
First we need a von Neumann swarm... spacefaring drones which can harvest materials from asteroids and 3D print whatever we want, including copies of themselves.
First get them to self-replicate into a hugely productive distributed factory and then start printing solar panels, ships, space stations, Death Stars, whatever we want.
