Apart from my language trips and language courses I also was involved in several language tandems on my home turf. You basically meet with a mother tongue speaker of the respectively other foreign language who for his part wants to learn your mother tongue. Ideally both have more or less the same language level.
The advantage for both sides is that this way of learning or practising languages is free of charge for both sides as well as independent of time and place, meaning you are not bound to the schedule of a school and can determine the meeting place by yourself. For me personally tandems were a good enhancement respectively a way to get more fluent after learning the basics of a language and to improve pronunciation, erase errors and learn more vocabulary.
I tried tandems in pretty much all languages that I speak but to be honest they usually never survived more than a couple of month. But this of course depends on yourself while you can always can look for a new partner if things don’t work out with the current one for whatever reason.
Best places to find tandem partners include the internet as well as notice boards at universities, language schools etc.
In Würzburg I made some good experiences with the following two options:
Facebook https://www.facebook.com/groups/746386448704683/?fref=ts (almost 1.000 member at the moment)
Uni Würzburg Face2Face http://www.zfs.uni-wuerzburg.de/mediothek/face2face/ (1.000+ tandems since ’09)