I'd focus on restoring Earth's ecological health before it's too late, and making life on the planet self-sustaining and maintainable.
Ecological policy (generally priority 1):
* Halt most conversion of land to human use.
* Restore natural environments and prevent extinctions, restoring plant and animal habitats and ecosystems.
* Increase research into ecosystem health.
* Put fishing under control of scientists with the goal of restoring oceanic health, preventing extinctions and achieving eternally maintainable fishing levels.
* Research and develop fusion, solar, wind and tidal power.
* Phase out coal, petroleum, and fission power.
* Research and develop very low-emission vehicles.
Social/political policy:
* For-profit corporations will be re-chartered so that their mission statement is to do things that benefit humanity in some way other than making investors richer.
* Acceptance of the right of communities to define their own rules which may conflict with other communities. The United States, for example, will evolve to states (and in some cases, counties and cities) which each have different laws to fit different communities - people will be encouraged to move to states which have communities and laws that match their belief systems. Some other parts of the world where people are caught in genocidal conflicts, may need to be segregated into their own communities.
Urban design:
* Redesign modern urban and suburban areas to be pedestrian-focused and connected by public mass transportation, rather than automobile-based communities. Most American suburban communities will be re-forested, etc.
* Urban renewal will preserve historical and interesting architecture and destruction of old buildings will tend to be done first (or only) to structures with no redeeming aesthetic value.
Information technology:
* People will have the right to anonymous free data access, anonymous encrypted private communication, and free uncensored expression as long as it doesn't hurt others (e.g. child porn), and to ignore whole categories of content.
* Copyright and intellectual property laws phased out through a schedule of increasingly shortenned expiry, and eventually replaced by new systems which reward individual content creators but quickly open up content to free access to published works by all.
And other stuff...
