Matt Laur , Jul 20, 2008; 04:17 p.m.
Try using a reflector to help fill in the harsh shadows you get in bright overhead sunlight. You can fill with a flash, too, but that can look a little too artificial if you don't know how to balance color temps. If you use a reflector, you know the light balance will look right, since it's the same light that's coming in from overhead.
You might look over some of these quick free tutorials. Obviously they're really a pitch for Photoflex products, but I think you'll find them helpful. There are at least two that show how effective a couple of reflectors can be when it comes to dealing with hard sun-related shadows. Your subjects may find themselves dealing with some very bright continual light in their faces, though, which can make them squint, and can make their pupils contract in a less-attractive way. One trick is get them posed, and have them sit with their eyes closed. Then, 1...2...3... "open your eyes!" and CLICK. You'll have to play with they idea.
In open shade, fill flash is the magic bullet. Attached is a simple capture made on a bright day, but under a tree throwing solid shade. I metered for the sky in the background, and then adjusted my on-camera flash (in my case, a Nikon SB-800) to fill in. If you know what you're looking at, you can tell the subjects are lit with a flash - but it beats having them squinting in the sun, having big eye shadows, etc.
Fill flash in open shade on a sunny day.