Student organizations act as job agencies as well as administrative bodies. If you want to maximize your chances of finding a fitting job, you can be a member of more than one student organization at the same time. The student organization will ensure that your employment is compliant with regulations. For example, proportionately, your salary cannot be lower than the current minimum wage.
Depending on what you do and how much you work, being employed through a student organization might pay better than being employed regularly. This is because serious tax benefits apply: you are not required to pay the social security contribution (18.5%), while your actual employer does not have to pay social contribution tax (13%) on your work. In either case, if you are under 25, you do not have to pay personal income tax at all (otherwise it is 15%).
If you develop a good working relationship with your employer, they might be willing to employ you full-time after you graduate. Then you have to switch your student permit to a work permit, with which we are happy to help.