Improving English language skills

I'm a native German Speaker with English as my second language. I'd like to improve my skills in the English language but don't know how to. What I currently do is watching English movies and writing in English forums such as 4chan. The problem is, by watching movies I'm just a passive actor, it's no practice. Writing in forums is, but I get no feedback (what's important to improve skills, I think) and/or write simple sentences only.

What do? Maybe I should join a community full of grammar nazis, giving me no room for errors without being admonished, but does such a place exist?

엔 잇세 비때 시이대 아야둑셋다, 엣대 헤 사이시팟 올라 피바이나 다팔릿덴 이흐
밋덴 요우곳사.

不ん自想だしいた考クせスた、えった他許いしヴぁト居っら自由いな普っりスてん人スてん組こっさ。