Dear my friend,

You should definitely check some webpages that my friends have suggested. I also am a student in Germany and there are many part time job opportunities. So If you want to make money while studying you should definitely work. If you are a good student than you should also apply for scholarships. Here are some scholarships you may find interesting:
http://www.frankfurt-school.de/content/en/education_programmes/doctoral.html
http://www.mawista.com/en/scholarship/
http://www.hhl.de/en/service/financing-options/
Only with hard work you could achieve everything in life that you need.
Alma