When outdoors, wear some kind of hat. Even people with a lush, beautiful mane (unlike me) still need something between them and the sun. Hats keep heat stroke at bay and take the brunt of stray baseballs and hockey pucks (instead of hair tufts and chunks of scalp).
No matter which style hat or cap is chosen, avoid logos and go for the darkest colors.
Photojournalists cannot appear biased. A Viagra cap may send the wrong message some places. Likewise, nobody wants a conflicting cap with an event sponsor or subtle problems may arise. For example, I would never advocate wearing a Washington Redskins cap to cover a Dallas Cowboys game.
Dark-colored hats absorb more light and heat. However, the darker shades won't reflect off subjects. It also helps camouflage the photojournalist. Even if the camo ability of the hat only works for one frame, it was worth it.
Overall, I suggest a boonie hat. It keeps the sun and rain off our necks while it shades our eyes.
You'll need to know your hat size at your typical hair length. Small, medium, large versions are made, but sized hats with military tags are best.
A huge advantage to a boonie hat is brim flexibility. It moves out of the way to allow us to shoot with our forehead pressed against the flash. Then we flip it back down to shade our eyes and keep our eyes from reflecting off the eyepiece.
Cleanliness is another great advantage to a boonie hat. A boonie hat can be machine washed. If you've ever covered a rodeo in the wind, you'll immediately welcome this idea. However, don't put it in the dryer. Instead, flatten the brim while it's still wet and lay it on a counter to dry.
The down side is the "dork factor." If we forget to put the brim back down after the shoot, we look a little intellectually challenged.
Enough for now,