Outdoor Portrait photography
When photographing subjects outdoors, place your subject in open shade and use a reflector to bounce light back on to your subject.
When placing your subject in open shade make sure that there is no dappled light making its way to your subjects face. If there is dappled light try to place the dappled light to your subjects back or use a scrim or gobo to block the light.
Once you have your subject in a good spot have your assistant take a reflector and hold it over their head so that the reflector is at a 45 degree angle down and at a 45 degree angle to the Left or right of your cameras position.
The reason for holding the reflector up is to simulate the suns position. Many first time photographers place it low so the light bounces up on to the subject. Where this will fill in under the chin and eye sockets it will produce an un-natural light.
If you do need to get some extra light under the chin place a white reflector so that the shaded parts of the face will be filled in. Remember; when using this technique to not overdo it. You only need a little bit of light to fill in the shadow not completely remove it.