Do your homework
Before the interview learn as much as possible about the company: read the website blog, LinkedIn profile and Facebook page carefully. Find the people you are going to meet online: if you are lucky, there is useful info on a web page or linked profile.
If a person writes a blog: read it to know what she/he is concerned about. Probably there are some tips of what to expect during the interview.
Consult with services such as glassdoor.com or kununu.de for some specific insight of what type of interview is common for the company and even what questions to expect.