What's my name?
In Germany, we typically write the given name first (my given name is “Roman”) and the family name (“mine is Klinger”) after that (hence, “Roman Klinger” is my full name). That means, contacting somebody you don’t know personally and you are not close with in an appropriate way would be with “Dear Mr Klinger” (or Dear Dr Klinger, if you want to be super-formal, but I don’t care). I would also be fine with “Hi Roman” or “Dear Roman”. What would be weird is “Dear Dr Roman” or “Respected Mr Roman”, though I receive that pretty often. That is a combination of the informal use of my first name with a more formal “Dr”. Similary weird would be “Dear Klinger” or “Hi Klinger”.
So, if you are not sure, contact me with “Dear Mr Klinger”, or, if you want to be informal with “Hi Roman”.
If you want to learn more about differences between names, I like the following links: