I use Super Clean and warm water with a nylon bristled brush to clean the surface, then ammonia water with a sponge and finally a rinse with a water softener like Calgon and water. The Calgon makes the final rinse sheen and not bead up and water spot.
Then I coat with CorrosionX 61002 Rejex 16oz Bottle
https://www.amazon.com/gp/product/B0006V0LNY/ref=oh_aui_search_detailpage?ie=UTF8&psc=1Read the reviews and see if it's something you'd like to try. Pricey but lasts a full year easy. I've used it on everything from fiberglass, gel coat, metal, even lexan and helicopter canopy. Nothing sticks to it, bugs rinse right off.