Screw money, make the world a cullminating society, move everyone from 3rd world countries to emptier places like Canada, Europe, US and Russia. Then turn Africa into massive amounts of farmland and ship workers over there to plant, spread manure and harvest. Then unite the world under one federal parliamentary democracy that speaks a new phonetic language. After that, demolish religion. No more war, people work to help others, instead of for their own benefit and others work to help them. Now, we need to rework our educational system to avoid Phys Ed, Music, old languages, even the new language, to focus on Math and Science, so we can actually make advances in technology faster. Then, as a world nation we'll need to work towards some sort of pill that makes us live forever (nanobots, perhaps?), then we'll need to cure all diseases, then find a way to instantly implant all knowledge in the world into one person's mind, then use it instead of school.
After this the world will probably find alien races within my predictions, 5-10 years, and create some sort of Intergalactic Trade Agreement between the World Nation and this alien race. Then, as we find more alien races, we must at least ATTEMPT to unite the whole universe under one government similiar to how we have on Earth.
Also, death sentences for any crimes. Stops people from commiting crimes and helps control population of criminals.
Also, colonize the moon, mars and venus. When population becomes a large enough problem we need to ship them there.
There, the world is fairly perfect now.