Squinting while at the beach or a bright location, especially when you have a scrim overhead to cut the light a bit, or some type of open shade and have to pop fill in from reflector or even a natural reflector?
Real easy, go to K-Mart of Wallymart (the latter I despise) and purchase some black tule (also spelled tulle) and lay it over your reflector. In photography black is not a color, it's a tone, it will not change the color of the image, it's almost like a "black scarf" (found in our tips section) on front of your camera lens. Make sure the tulle is very sheer so the reflector still reflects, works like a charm, gives the model something black to look at and since black (in it's purest form) absorbs 90-percent of the light that hits it, helps the model stop squinting. It's also a great idea that you wear at least a black shirt too and if your head is bald, wear a hat (grin).
Just some fyi, as I'm working on my second book, I was thinking about this concept and wanted to share it with you, it works like a charm..thanks, rg sends!