Application & trial period
Application
Applications for advertised projects as well as unsolicited applications should be submitted in writing (usually by e-mail). Verbal applications are only recommended if they arise in another context (course, HiWi job, etc.). In the interview or a consecutive follow-up interview, you should discuss the topic of the job, conditions and expectations as detailed as possible and put them down in writing.
Trial period
Agree on a trial period for literature research, familiarization, statistical consulting, etc., at the end of which you (not your supervisor!) write a one-page project outline on the objectives and methods of the planned work. This is valuable for both you and your supervisor to get an overview of your state of knowledge.