Requirements for German working visa

To get a normal German work visa, you need to find a German company willing to hire you - and that company has to show that there are no suitably skilled EU citizens that they could hire instead of you.
(Steffifi is right in saying that to find such a job, you need good qualifications, niche skills and usually also language proficiency.)

Alternatively (i.e. if you do not yet have a job offer), you can apply for a Blue Card, which allows four years of working in Germany, if you are a highly skilled person (minimum recognised university degree) in certain disciplines (natural scientists, mathematicians, architects, interior, urban and traffic planners, designers, engineers, scientific engineers, physicians (except dentists) and those with academic qualifications in information and communications technology).

Another alternative, if you are below 30 years old and come from Canada, Australia, Brazil, Chile, Hong Kong, Israel, Japan, South Korea, New Zealand or Taiwan, is the Work Holiday Visa, valid for a year and allowing temporary jobs.