Here's a live shot from today. It was a sunny day, so I backlit with the sun. Reflector in front to light the talent, double net scrim overhead to knock down the sun on the shoulders, clamp on camera flag to keep the sun off the lens. Pushed into the shady side of the backround. I avoid direct frontal sun if at all possible.
For outdoor, daytime stand-ups we usually roll with an 800 HMI, 4x4 or 6x6 with either 1/4 silk or full stop silk, sometimes a reflector or Astra for fill, if needed. And obviously, try to avoid shooting a nuclear background, especially if you're in the shade and don't have natural light helping illuminate the talent. I used to use black nets for the background a lot back in the SD days, but haven't been a fan in HD. As a matter of fact, I think I threw most of mine away, because they dry rotted.
Placement is key! If you can, get to the other side of an object so the sun is working with you, do it. Avoid high contrast situations (shade and full sun in same the frame).
Suggestion: Keep a 5 in 1 collapsible reflector handy. They can be had for about $40-$50. Bounce light into the subject off the silver reflector.
Bright objects will make people squint, no matter their origin. The sun, a bright light, a reflection of either off a mirror or a car window. If its bright out your talent will just have to deal with it. You can help them rest their eyes between takes by having them look away from brightness or close their eyes for a bit.