Enhanced Raman spectroscopy is a valuable tool for detection of low concentrations of molecules. For this reason, surface-enahnced Raman spectroscopy (SERS) it is a suitable method for inspecting functionalized graphene. However, for a proper understanding of the metal-graphene interactions we focused also on the the enhancement of graphene itself. For example, we investigated the SERS effect with isotopically labelled bilayer graphene, and its behaviour under different excitation wavelengths and plasmonic metals. The Raman signal of molecules is enhanced also in the vicinity of graphene by graphene-enhanced Raman scattering (GERS). In our work we experimentally probed the theoretical expectaitons fro GERS using functionalized graphene.