Question to help Rock Climbing

Hey whats up guys,
Im an amatuer rock climber and grip plays an important part in the sport. Thing is, i lift 4 days a week to help my performance on the rocks, but my grip just never seems good enough. Whether it be bench pressing or climbing 300 feet on a rock I feel week when it comes to my grip and wrists. So my question is... does anyone know an excercise or anything to help stregthen grip alone. I do forearm curls and have even tried those little rubber balls you squeeze and all those sorts but they dont seem to help. anyone?? please?? lol thanks in advance i just wanna have a nice firm grip when i go to shake my fiance's fathers hand. hahaha