The polishes and cleaners you use for painted metal surfaces are not effective (in my experience) when used on fiberglass.  I have been looking for a complete kit that was specific for fiberglass.  I have a Honda riding mower and a fishing kayak whose surfaces have been neglected because I've never found a product that is designed to detail fiberglass.  The Meguiar's M4966 Complete Marine/Rv Fibergalss Restoration Kit is unreal!  It cleans and resurfaces dull fiberglass and brings the surface shine back.  It still requires elbow grease however, so be prepared to be a Karate Kid - "wax on, wax off" :)