I use scotch brite with car paint scratch remover to clean the rim braking surface, and sand of the glazing from the brake pads. It seems to work very well for me. I have used kools top brake pads for wet conditions, but found that the compound was too soft and wore down very quickly in wet gritty conditions. Furthermore in my estimation the breaking efficiency under wet conditions was only slightly better than the Shimano pads that wear considerably less under the same conditions.
YannisG