This part of the guide is not foreigner specific, but can probably help anyone.
In the first part I will show you some contract templates, that you can use. I created this documents mainly for myself, but they will be helpfull for you too.
In the second part I will show you typical templates of a business letter and a CV. I noticed that the styles differ very much in different countries, so just take a look.
C.V. / Lebenslauf
For C.V. and Lebenslauf I recommend you using the EuroPass Template, which allows you to easily manage and create a standard CV. It is a free services provided by the European Union. It gives you a good idea what to put into a C.V. (and what not) by providing examples.
Contracts and Flat
This is a sub-rent contract (Untermietvertrag). The person renting the flat can have this kind of contract with another person renting another room, or if you are letting your room to someone else for a limited time.
→ Untermietvertrag Vorlage / Example Sublet contract
For writting formal German letters there is plenty of good documentation. As a start I recommend you this link.
→ Writing a letter in German: Formal Letters
Latest Change: (Updated August 2015)