Assume you've been given sovreignty over a land:

Obviously what you do depends on what kind of area you get, but here's a few things I could do almost anywhere:

 Spoiler

Basic stuff:
- Tax religions if they aren't
- Seperate religion and state if they aren't
- Seperate religion and education if they aren't
- Get women the same rights as men if they don't already
- Gay marriage
- Any group/religion that infringes on human rights is forbidden/banned

Goals:
- Focus on education, science and engineering
- Net neutrality
- Modern patent and copyright laws
- Green energy and fuel
- Good health care for everyone

Government structure:
- National elections
- Every vote has the same weight
- 150 seats
- Majority of 100 votes needed to pass something
- All laws need to be reviewed at least every 15 years
- Anyone can create a party
- Pro- and anti-religious parties are forbidden
- Full transparency

Basically focus on creating a stable and futureproof nation. All the things up here are put in the constitution, including the goals, so even if I wouldn't get elected again things would keep moving forward.