Try to figure out if it is paint on fiberglass or gelcoat.
If paint then wash & wax like any other automotive finish.
If it is gelcoat and it is dull and or chalky I currently use Protect All
Fiberglass Oxidation Remover & Color Restorer
It requires some effort.
For wax, I use Protect All
Polish, Wax & Treatment
It contains Carnauba wax and is the easiest wax
I have ever used. Literally wipe on and wipe off
. I use it on my car and my RV.
Protect All is one product that DOES IT ALL: cleans, polishes, waxes, protects and treats all surfaces -- front to back, inside and out. It is quick and easy to use and leaves an anti-static, water repellent lustrous shine on hard surfaces, while treating the vinyl, rubber and plastic.