Desirable subject-specific and interdisciplinary knowledge
It is helpful if you had a good grasp of math, physics, chemistry and German at school. Knowledge of English is important, as technical literature is often written in English, project groups are usually international and technical English is used in technical and negotiation discussions.
Basic PC skills are also an advantage, but you do not need to be proficient in programming languages. Do you enjoy manual work such as soldering or assembling circuits? Did you take technical subjects at school and are you interested in technical or electronic contexts in your free time? This will make it easier for you to start your studies successfully.