[Abjatrer]

We all have the problem of them shields getting scratched by this or that, what "solutions" do you know about? besides eventually getting so pee'd off with that vertical streak in your vision, you go and buy a new shield.
Heard of the cleaning it with toothpaste, letting it dry and washing it off - but it does not make a diff IMHO.
I like to see clearly where I'm going....
... dodging cagers and sheep and bugs and cats and pigeons..... etc....

[Denied]

Assuming that it's not an iridium visor the best thing to use is metal polish.

I personally use Mothers aluminium polish. Once I've got the majority of the scratches out use AutoGlym Resin Polish to finish the job.

Make sure that you only go in one direction ie from left to right across the visor or up and down otherwise you will end up with nice tasty swirls all of the visor making it just as unusable as when it was scratched!

The bonus with doing this is that water will now just SLIDE off the visor and bug guts don't tend to stick quite as well.

Hope this helps