This cumulative habilitation thesis presents different concepts which can be used in the bottom-up fabrication of molecular electronics. Most striking, the functionality of a single-molecular switch is demonstrated, which is based on the rotation of a chemical bond under the tip apex of an atomic force microscope. For embedding such molecules into a large assembly of individually addressable devices, however, not only the molecule but also the substrate properties are of utmost importance. Therefore, we investigated three surfaces with tuneable or structurable properties which is essential for the self-assembly of molecular devices. First, the characterisation and manipulation of ferroelectric domains on the nanometre scale is presented, second, thin films of a novel photolabile terpolymer are structured by UV illumination and facilitate a selective metallisation on nonilluminated areas, and third, ultrathin spacer layers are investigated which tune the substrate work function and the vertical interaction to the ad-sorbed molecule. The latter ultrathin films on metal surfaces have been applied in such a way, that the cluster formation of organic adsorbates on these films is influenced via an appropriate choice of the underlying metal substrate.