Nation building is, apparently, difficult.

After watching it go wrong repeatedly, I think we need to professionalize the process.

I would start by putting a dedicated person in charge about 3 years before the invasion.

Day 1 is establish food, water, and safety. Flood the country with trained police (not soldiers). Deliver food and water to each individual (to prevent local warlords from taking it.) Take down dangerous buildings.

Day 2 would be housing and medical care. Build simple, but safe housing. Expect people will love in it for 50 years. Build and staff medical clinics and hospitals.

Day 3 remove rubble from roads.

Day 4 build prison and court systems. There will be some very bad people that need to be removed from society. Put them on public trial, but not show trials. Everyone will be watching, so don't fuck this up.

Day 10 or so, start schools for educating the children. Teach adults to read, write, and basic math. Educate with an open hand, few will trust the government at the start. These can start as glorified day cares, so adults can focus on fixing things.

Often, dictatorships split the population into groups to keep them from working together. A truth and reconciliation group will be needed, similar to in South Africa.

After it seems there will be no genocide, then fix the transportation system to allow easy and free movement of the people and goods.

Adjust plans for local conditions.

Do not put locals in charge until after things stabilize and they have been investigated.

Do not allow anyone connected to the dictator to run things. This includes their cleaning lady and caterer.

Get the local economy back to working. Very slowly reduce outside support for things that can be made locally after ensuring there is a local supply by the government buying the final needed amount. (Consume locally or export.)

Investigate and prosecute corruption.

After a couple months, setup free and fair elections at the local level. As things go well, expand to the next higher level of government. Keep the expansion slow (like every 10 years). This allows those not affiliated with the director to build skills and learn to not be corrupt. This will help locals express their needs and coordinate.

In 30 or 40 years, of all goes well, pull out and let them self govern. Invite them to join your country with unrestricted movement of people (so you better have done a good job.)