I think this guide is not too bad [1]. Some stuff depends on the business you are in and the company you are applying at. Listing the marital status used to be very important, but I don’t believe it still is.
German companies love official certificates, as if they really prove something (most time it doesn’t imo)
As most people here, I am working in IT. Since there is a demand for us, I don’t feel like I really have to stick to those rules. For example, I gave up on having a German CV, even for non international companies. I was tired of curating two CVs. Companies expect us to be proficient in English anyway, so I expect the same.