You can look in facebook for groups like "Neu in (city)" or to speak german search for "Tandem (city)" to find people who are looking for a tandem partner.
You can also check on couchsurfing.org for local events, they usually have weekly meetups in bigger cities...
there is this website called meetup.com where you can find local events as well
If you tell us where you live we can give you more advice =)