Be careful of products containing bleach.
They can discolor and remove things you wish they didn't, especially on graphics.
I have had good luck with two products on mildew/mold.
Wet & Forget (mentioned above)
I have only been using this product recently.
I didn't know it existed until about a year ago. Not sure how long it's been around.
The other I've been using forever,
It's called Jomax.
Originally designed to be added to paint to keep mold/mildew from forming, it is now marketed as a cleaner. You do mix it with bleach but the Jomax reacts chemically with the bleach to make it safe to use on all surfaces. I find it in most big box home improvement stores. It works wonders on awnings too!