Here's my #1 tip for outdoor portraits: Control the light with a reflector, diffuser or a flash. All of these accessories have something in common: they can reduce the contrast range in the frame, reducing or eliminating harsh and unflattering shadows. A flash and reflector can also add a nice catch light to a subject's eyes.
Check out the top row of pictures. The girl's dad is holding a diffuser (actually from my Light Control Kit) between the sun and his daughter's face. Look at the harsh shadows on his face. Half of it is hidden in a shadow. The other two shots in the top row show the beautiful effect of the diffuser.
The bottom row of pictures illustrates (L to R): No diffuser, diffuser, diffuser/flash.
Control the light and your subject's faces will light up when they see their pictures.
Explore the Light,
P.S. My camera for this shoot? My trusty Canon G10.