Well since I'm located in Sweden I've initially focused on how to set up a non profit organisation here. And the process is pretty straight forward. Until you get to taxes, salaries, expences and such. Even if you are a non profit you still need to pay employer fees, taxes on salaries and pensions, if you have employees or any salaried personnel or consultants. If they are volunteers but have expences well they need to be declared. But all that would be normal business for an accounting.(I'm not an accountant)

Basically to get started you need to have a charter, voted on at the first board meeting. After that your organisation is born. Then comes registration, getting an organisation number, setting upp tax accounts, bank accounts, seeking grants and subsidies, an office(for lack of a better word) if needed. Also the non profit needs to have a mission that is to the benifit of society, a bit of a open interpretation here, but it can't just be "let's have a we three men go on fishing trips non profit". Oh and yes it needs to be open for anyone to join (there are exceptions here. But that needs to be stipulated in the charter. Think a historical society, excluding history revisionists, or that dude from ancient aliens).