In the field of rare physics events experiments the background reduction plays an important role to distinguish the feeble signal under study above the background. Low level counting techniques are continuously under development to improve the measurement sensitivity. In my presentation I will summarise my contribution in the development and optimisation of both detectors and methods for high sensitivity measurements. I will focus on three main projects I have finalised during my career up to now using germanium detectors. The projects have different purposes spacing from material screening and selection for rare events experiments, to the investigation on natural and artificial radioactivity until the rare decay searches. They are a gamma-gamma coincidence spectrometer, the optimisation of a BEGe detector and the development of a HPGe Array. I will then present the duties and the achievements I reached during my current researcher position.