An overview of the job opportunities for physicists can be found at Welt der Physik
Support for your career start is offered by the Career Center of RWTH.
The Studentinitiative Bonding organizes fares with companies and allows the contact with potential employers.
For example the Job Shadowing is a very interesting opportunity.
Similar options offers the so called Mentoring program of the German Physical Society.
On the pages of the Career Center you can also find tips for your applications.
Other intomations about the start into the job you can find on the web page Berufsstart.