If you like to improve your English by not surfing the net or doing exercises you should try watching films in English (sometimes English subtitles help, but not the German ones).
You should have an app on your mobile or tablet from the important newspapers in the USA or Britain.
Try to read some articles a day. It is worth taking the time as you are up to date with the news and get good English practice.
One interesting chance of improving one’s English is listening to audiobooks or reading the print versions.
There are lots of free audiobooks on the net. On the following web sites you have a good selection:
You can have the free audiobooks as an app for mobile device as well. Please have a look at your app store or google play store for further information.
Your local library (including GSG) has lots of English books and audiobooks for free.
Other web sites that are helpful: