[quote=@Shovel]
Any suggestions on policy making, writing, and the whatever that related to nrp are much appreciated.
[/quote]
When it comes to writing posts for an NRP, the most common is to have it take the PoV of one or more characters. Typically this is the head of state, getting information and letters from other branches of government. Sometimes depending on the scale of the NRP you might have additional characters filling in for other departments of governments. Like an Economic Minister trying to improve infrastructure or a War Minister worried about the nation's ability to wage war or a Diplomat conducting relations with someone else. Sometimes it might just be a random civilian or soldier if you want to get a feel for the day-to-day, on the ground look at what the big policies are doing to people.

A slightly less common way is to have it be like an After Action Report or history textbook/wiki article where the focus is on the country/state and the names of people isn't as important. This way you can write in broad strokes without worrying about character details of individuals.

"King John Smith received a letter from the notUnited States and decided to support President Bob in the war."
VS
"The Kingdom of notGreat Britain watched the developing war, finally declaring support for the notUnited States in 19XX."

That's probably a pretty terrible example but it gets the vibe across.

[quote=@Shovel]
how do I make the policies and the subsequent situation to not be an outright nationalist's wetdream? 
[/quote]

It comes with exprience and maturation. Just like how people's first OC characters are often overly edgy, mary sues or otherwise of questionable quality when looked back on, people's first OC nations can come off as overly militaristic, some how utopian and otherwise societally implausible; some how having all the resources it needs, a jingoistic and militarized population to make 1930's Germany blush, the world's most advanced military, and a free and uncensored press with no government corruption. I will be the first to admit my early nations in NRPs were basically like this with a heavy coating of weeaboism (I made a [i]lot[/i] of notJapans.)

As to how to make policy and navigate situations, realize that no matter what setting, governments always have internal competing interests and that compromise is a common occurrence. A king might want to go to war while his vassals don't. A president or faction might have ties to big business but the population itself is going through a socialist/communist wave. A military command might think that the country is in danger by some external power and demand military build up while the civilian government insists on diplomatic channels and civil spending. This idea of unilateral support for a government's action never really happens with 100% of the pop agreeing to it unless it is some kind of absolute autocracy or dictatorship where this kind of internal politicking about what do can be more easily side stepped with "obey or get shot".

Also realize that even if you are playing this hyper nationalist country, you're ultimately in an RP. Don't stake your personal image and beliefs, this love child of a country you may or may not wish actually existed, on its success in an online post by post roleplay. Its a really small and pretty stupid hill to die on. When you RP you should be working together with the other players to make something fun and interesting; its a collaborative effort. You can play the all consuming notZerg hivemind swarm but how much you'd actually be able to conquer is still up to the GM and other players. Nobody likes getting rolfstomped without recourse so talk to people, discuss plans, collab on posts. We have the luxury of being able to know when and what exactly happens unlike in irl history so use it.