You are studying in Germany and your studies should be your main focus. If you would like to find a temporary employment and get some work experience during your stay in Germany, you should keep in mind that there are some restrictions:

The secondary clauses in your residence permit are of critical importance. They specify to what extent you are allowed to work in Germany. Generally, students are allowed to work up to 90 full work days or 180 half days (maximum of 4 hours a day) per calendar year. Work days on which you work no more than four hours are considered half days. It is irrelevant, whether you work during the semester or during the vacations. The same applies for the so called "minijobs" which allow you to earn up to 400,- € a month without any payroll deductions.

If students don't work longer than 3 months in a calendar year, they don't need a work permit.

If you work at more places at once, only the number of workdays matters.

The same conditions (the possibility to work without a work permit for 3 months / 90 full work days /180 half days apply also to temporary employment.

All further employment over the 90 full days or the 180 half days a year requires a work permit. In this case it is advisable to contact the local Foreigners' Registration Office (Ausländerbehörde) before you start working. Only in exceptional cases an exemption to the secondary clauses of the residence permit can be made. The Foreigners' Registration Office, together with the Employment Office (Arbeitsamt), will review the case and decide whether or not a work permit can be issued.

A job of an assistant at a university or research institution is possible without a work permit, if the student is occupied primarily with scientific tasks.

For internships that are required by the study and examination regulations students do not need a work permit. In this case, the internship is part of the study plan and students are no employees as long as they are enrolled at a university. This also applies to Master's thesis produced at a company. However, students do need a work permit, if they are employed at a company or do a volunteer internship, provided they have already worked for 3 months or 90 full work days or 180 half work days in the particular year.