We report numerical simulations of the coupling of waves, either propagating or evanescent, with the eigenmodes of dielectric nanocylinders and nanospheres upon substrates. The multiple interaction of light between these objects and the dielectric surface at which the evanescent waves are created is taken into account. In this way, we present an accurate procedure for predicting and controlling the creation of large field enhancements concentrated both within and near the nanoparticle compared with the angle of incidence and the state of polarization.