In this seminar I will give an overview of my theoretical PhD studies on nonlinear effects in plasmonic structures boosting the intrinsic material nonlinearity through the resonant plasmon field enhancement along with a nanoscale confinement of surface plasmons. A number of problems, including formation of plasmon solitons, frequency conversion and complex nonlinear dynamics, in hybrid plasmonic and graphene-based setups will be considered. The analytical models and results I will present could have important implications for nanophotonic devices and nonlinear optical elements operating beyond the diffraction limit.