Everyone who rides motorcycles (and wears a helmet) will sooner or later need to clean their face shield. This article is about a simple and easy (home made) way to clean yours without a lot of effort, no chemicals, and without scratching the shield either.
Just take a couple of paper towels and get them soaking wet. Then drape the wet towels across your face shield. Let it sit for 3-5 minutes and pull it off. Most of the gunk on your shield will come off with the paper towel, and the rest has been well softened and loosened up so that you can easily wipe it off.
Using a really wet paper towel and waiting is critical. This lubricates and softens up all those bug guts and exoskeletons that get plastered on your face shield. Then when you wipe them off, it does not leave scratch marks or otherwise ruin the visibility through the plastic.
This same approach will work on sunglasses; a windscreen, or any other soft plastic you may need to clean. One caution – do not leave the paper towel on there and just walk away. It will dry on there and you will have a worse mess to deal with scraping the paper pieces off too.