I only get one country? Fine, I rule USA, take over entire world with their (admittedly large) army, force everyone into marshal law, zero tolerance on rebellious uprising, re-write world laws and enforce 'eye for an eye' policy, ban all non-state regulated imports and exports, cancel third world debt and make sure the third world creates a system where they can sustain themselves, two years national service for EVERY citizen, abolish prisons and create penal work forces to help third world and any other unskilled labour needed on earth, ban organised religion and give all church/mosque/religious lands back to the state to be used for something worthwhile (for instance hospitals, emergency services, public houses etc), people would get paid by what they produce rather than whatever stupid system it is now (sports stars get paid next to NOTHING because they don't deserve it, actors get a lot less, musicians get paid the same but no longer have to be backed by a publisher thanks to the miracle of internet, etc) and finally i would divert all remaining government funds and all available research to medical breakthroughs and, more importantly, space exploration! We need to colonise mars, then titan, then build an interstellar wormhole gate orbiting neptune, so we can get out of this solar system before the sun dies in 5 billion years, or humankind is toast!!!
Or something like that, I really haven't thought about it a whole lot... ¬_¬