Natural light makes beautiful portraits just remember shade is your friend. Pick a large tree and put your subject in the shade on the edge facing the light. Remember to keep them in the shade and I think you will love the results of this lighting. Skin tones will be natural and there will be no squinting from being in full sun.
If you must take a portrait in full sun always use side lighting for the best results.
Pick the best time of day for your pictures. I prefer to take portraits before 10:30 a.m. and in the evening about 2 hours before sunset.
Lighting is the key to good photography and it will make a huge difference in your pictures.