There are several ways to ask what someone does for a living: The simplest would be: Was ist dein Beruf/Job? Beruf means profession, but job is more oriented at the actual work. You learn a profession, but this does not mean you also work in that... You can also ask: Was machst du beruflich? (formal: Was machen Sie beruflich?). Was arbeitest du? Als was arbeitest du? Here you ask for the activity, the status in a company etc.

Was machen Sie beruflich?

Sorry for being off topic: I was once ask by somebody from the Schwabenländle: "Was schaffst du?" It took me (a real northerner) some more questioning to find out he wanted to know what my work is.