... have a side job in addition to my business
You are working as a freelancer or a self-employed person. Apart from working for your own business, you have or are looking for a part-time job.
Extra income and social security
You take a job on the side to earn extra money. How many hours per week can you and will you spend on your second job? The Tax Service only recognizes you as a self-employed person if you work a minimum of 1225 hours per year in your own business.
By working you also build up entitlement to benefits during illness and sometimes to pension benefits. On the other hand your employer will have the copyrights to your work unless you arrange something else in writing.
What kind of job
What kind of job do you want? An arbitrary job in a shop, café or restaurant? Or something more in your line, at a school or creativity centre? Consider what this job can offer besides money. Contacts with possible clients, for instance. Will this job do something for your network?