There is no better lighting than natural light.  If you stay out of direct sunlight you are rewarded with the warmest, softest light that wraps around you subject in the most pleasing way.  Here are two quick portraits I shot the other day using nothing but diffuse sunlight coming in through a window:

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1/320 second @ f/2.2, ISO 200, focal length 50mm

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1/160 second @ f/2.8, ISO 200, focal length 50mm