Register your company
In addition to your studies, you are allowed to work in the Netherlands as a self-employed individual, as long as you continue to meet the requirements for your residence permit for study. For AUAS bachelor and master students, please see these requirements here. There is no limit to the number of hours that you are allowed to work as a self-employed individual. Also, you do not need a work permit (TWV). You need to register your company with the Dutch Chamber of Commerce (KVK) and must pay taxes. Some people find it useful to work with an accountant to make their tax calculation simpler.
If you're self-employed, it might be necessary to take out health insurance from a Dutch provider. You can see what regulations apply to you on our Health insurance page.
This handy tool lets you fill in your situation and gives you relevant immigration information.