What's the best and easiest way to clean fiberglass showers?

Wipe down walls with your face cloth EVERY time you shower before you get out. My shower is thirty years old and still looks new and shiny. Easier to throw cloth in laundry than to deal with soap scum!

Ed, Marie M has a great suggestion for maintaining a clean shower. If it already is scummy, though, I use a soap scum remover. There are many brands out there, but I prefer scrubbing bubbles or lysol power bath. Spray it on, let sit for several minutes, then rinse or wipe off. It won't damage the surround. Use this weekly and it won't build up. If you have a build up, use a nylon scrubby to remove the residue while the soap scum remover is sitting on the surface.

Cut a grapefruit in half, cover with kosher salt and use as a scrubber.

Lysol Power Scum cleaner in the blue trigger spray bottle with a Magic Eraser or a scrub brush.

Wet & forget shower for a slower, no scrub solution. You can use 2x a week to accelerate the cleaning process then once a week to keep it clean.

Here is a great cleaner with no harsh chemicals https://homeguides.sfgate.com/cleaning-white-fiberglass-shower-90466.html