The most important thing you can do to start a successful business is to get help. If you have a mentor or an accountant, they will be able to carry out the trickiest aspects of starting a business and help you avoid the administrative and legal traps. They will also be able to advise you on how to make the business a success.
Local business clubs may be willing to help.
The local kommune probably has a business advisory service that offers help and advice for free.
The banks offer resources and help, some of it free.
You could also join or set up the 9 Conversations programme in your local area that will help you find the most important information and connections to start your business.
This website https://www.9conversations.no
Egen Virksomhed Nu (Your own Business now) http://egenvirksomhed.nu/
English version of Startup Svar (StartUp answers) https://www.startupsvar.dk/indexuk.asp