Dee Dee,
I like to shoot in open shade and use my flash, as David recommends, as a fill to warm up facial tones. I make sure not to have too much brightly lit stuff in the background because it will blow out when you balance for the people in the shade.

If you shoot under trees, be careful about dappled sunlight and make sure to use the flash. It will handle most of the shadows.

If possible, try to use a fairly large aperture to let the background go out of focus. That helps the people to pop off of the background.

You know what you're doing. Go and do a great job!

Jim