The Federal Employment Agency gives you here an overview of „Living and working in Germany“. This article, in English, also contains information about application documents and gives tips for job interviews.
Naturally, most students can do with a bit of extra income. Please note, however, that labor law regulations put some limits to the employment of international students. For many jobs, you also need to speak fluent German.
If you are a citizen of the EU, Norway, Iceland, Liechtenstein and Switzerland, the same regulations apply as for German students. While you do not need a work permit, you should not work more than 19 hours a week, otherwise you will have to pay social security contributions.
If you come from a non EU country, you are allowed to work 120 full days or 240 half days per year. If you wish to work more, you need a work permit issued by the Federal Employment Agency and the Foreigner’s Office.
Please note that this limit does not apply to mandatory internships which are part of your study program. A letter quoting the respective passage from your exam regulations will be enough for your company (the International Office can issue such a letter for you).
Once you have found an internship place, employers often want a variety of documents from you. You can read here which documents these are and where to find them.
While studying in a master's program, you should begin to plan your career in Germany. As an international graduate of a German university, you have numerous options in the German labor market.
Here are some tips:
If you have graduated from a German university, you have the right to stay in Germany for up to 18 months after graduation to find qualified work corresponding to your degree. This is particularly interesting for students coming from non-European countries. If you are planning to search for employment in Germany, please make sure to notify the Foreigner's Office before graduating, as your residence permit has to be extended.
The limit of 120 full days / 240 half days does not apply to graduates. During the 18 months of searching for suitable employment, you are allowed to work full-time for a living. For further information, please contact the Foreigner's Office.
You can find detailed information about employment by foreign students and graduates in Germany here.