There are two kinds of wind screens out there and it makes a huge difference on how you clean them. But, NONE of them will stand up to much cleaning with a paper towel. Paper is made from wood fiber and it just scratches plastics. Same thing with the window towels that you find at the gas station. They're made for cleaning, well, glass.
The first type (like the Concours) is acrylic, commonly called Plexiglass (which is a brand name). It is a harder surface, but it not very crack resistant. It is very weather resistant though. You can use isopropyl alcohol followed by a water rinse. Just be aware that the bug guts will also likely be abrasive to the screen so be sure you're not rubbing that bug back and forth across the screen. Personally, I just use a warm water soaked micro-fiber cloth, turning it often. Then, dry it with another one.
The second type, which you'll find on bikes like the Gold Wing, is made from polycarbonate, commonly called Lexan (which is also a brand name). Polycarbonate is very crack & impact resistant, but it's also very soft. As such, they have to put on a harder coating to protect the soft surface from scratches. Do a lot of buffing or use a compound on it and you're liable to work your way right through the coating. Once you expose the bare polycarbonate, you might as well start looking for another screen. Polycarbonate doesn't like the elements and will start to craze and haze up once the coating is gone. Many car headlights are coated polycarbonate and eventually all of the road crud will wear though the coating and that's why they cloud up. You can use the same isopropyl alcohol to clean the screen, just don't forget the water rinse.
