STASI tactics

The Stasi had formal categorizations of each type of informant, and had official guidelines on how to extract information from, and control, those with whom they came into contact. The roles of informants ranged from those already in some way involved in state security (such as the police and the armed services) to those in the dissident movements (such as in the arts and the Protestant Church). Information gathered about the latter groups was frequently used to divide or discredit members. Informants were made to feel important, given material or social incentives, and were imbued with a sense of adventure, and only around 7.7%, according to official figures, were coerced into cooperating. A significant proportion of those informing were members of the SED. Use of some form of blackmail was not uncommon. A large number of Stasi informants were tram conductors, janitors, doctors, nurses and teachers. Mielke believed that the best informants were those whose jobs entailed frequent contact with the public.

https://en.wikipedia.org/wiki/Stasi