If you start your company in the Netherlands there are many choices to be made.
First you choose your kind of business. Most new entrepreneurs already have an idea of what business they want to run. My advise is to describe this in a business plan.
Then try to find out who your competitors are. Find at least 3 of them. Find out where they are. Are they far away or nearby? Descripe in what way your service or product is unique compared to those competitors. Try to find a least 3 unique selling points.
How does your price match your competitors'? How many products or services do you think you can sell? Find out what the best price is for your product or service. This is easier if you make a financial schedule of what you need both for your household and for your company. Does this match your expected revenues?
An example:
This means your business has to make a profit of at least €2000 a month. Otherwise you can’t keep your household running. It is important to keep in mind that you can’t stop contributing to your household.
Your company will not be making a profit right from the start. Estimate your start up costs and the cost of running your company. Than ask yourself these questions: Do you have any savings or another kind of buffer that you can use during your start up time? How long will you last on that buffer? And if you don't have any buffer, what other possibilities do you have to fill the gap between starting your business and making profit?
If you are starting a shop take in consideration you need a place to store your goods, even if you are starting a webshop.
If you have figured evertything out, you can register your company at the Chambre of Commerce. Go to their website and fill the form to start a company. Choose the right form and use your business plan to fill it in. If the Chamber of Commerce has any questions, they will call you and adjust those parts in the form.