Another item in my sun protection gear - never leave home without it...
A hat with broad-ish brim that can be positioned just above the eyes. That will help greatly when flying just below the level of the sun, and reduces about half the total glare all the time.
Floppy hunting hats, like Cabela sells, work well and have the all important chin strap which is necessary whenever the winds finally get interesting.

Or you could go Aussie or cowboy to look cool. Make sure you can microposition the brim on the front tho. Baseball caps can work, but provide less protection from the sides. I got a nice one from Kite Connection, long bill and seriously down-turned sides that are very useful.
For sun glasses, I need Rx glasses so I specify "Real dark" and "Polarized", and get the largest frames practical.
BTW,
cataracts are a
standard feature of eyes my age. To delay the progression as long as you can, always wear dark glasses on bright days. (Cataracts, arthritis, poor balance, cr**py memory - a few features you can look forward to if you are lucky.)
As for cloudy days, having grown up in NW US (Portland, Seattle), my sensitive tiny blue eyes need dark glasses whenever there is a patch of sky not covered by
thick dark clouds. That is why sun glasses probably sell better here in the rain forest than other regions of the world. Think "mole people".