To make you really prepared you need to speak in German with native speakers. Speaking with non-native speakers would also help, but only if they are not native speakers of your language.
It's important to have a broad vocabulary, so there will never be too less learning. As for newspapers and news in TV, they are useful to learn the basics, but nothing more. The people on the streets are speaking with other accent, using other words. Movies (German ones, not dubbed!) are better ones, but the actors still speak more formal, trained language than the regular people.
So you could learn German for 5 years watching TV, and understand no word when coming there! Don't be surprised, from example of many people from Eastern Europe, you need at least 10 years of intensive learning to speak German maybe not fluently, but somewhere near that.
If you can't speak with native speakers, concentrate on German TV series and shows, look for some talk shows etc. Anything, where there are people from the street talking, or at least the actors imitating the people from the street talking.