We present a general route for the transfer of Au and Ag nanoparticles of different shapes and sizes, from water into various organic solvents. The experimental conditions for each type of nanoparticles were optimized of using a combination of thiolated polyethylene glycol and a hydrophobic capping agent, such as dodecanethiol. The functionalized nanoparticles were readily transferred into organic dispersions with long-term stability (months). Such organic dispersions efficiently spread out on water, leading to self-assembly at the air/liquid interface into extended nanoparticle arrays that could in turn be transferred onto solid substrates. The dense close-packing in the obtained nanoparticle monolayers results in extensive plasmon coupling, rendering them efficient substrates for surface-enhanced Raman scattering spectroscopy.