Hello, I am a native German and naturally good with German orthography and grammar. On top of that I have an excellent sense for expression and style in German texts, and when I proofread I detect any strange sounding phrasing as well, and can correct it. I have done several proofreading jobs before (just not here on Freelancer.com, but on upwork), mostly I work translating English to German. My clients were very satisfied.
For a simple proofreading (just minor grammar and spelling mistakes) I take 0,5 c per word, for task that require more editing, rewriting etc. my rates are higher, up to 1,5 c per word if you choose a fixed rate. For hourly jobs I take 13 $ and can possibly proofread around 2000 words.
Regards, Sve