Brush up on your reflector skills
To prevent your portrait-sitter from squinting into the sun, position them so their back is towards the sun, and use a reflector to bounce light onto their face, feathering the reflected light rather than bouncing it directly into their eyes. It’s worth experimenting with different reflectors. A silver one adds a clean, crisp quality; a white one gives softer results that are often easier to blend in. Gold reflectors add warmth.