Regardless of whether you use paint or a camera to capture your subject, selecting the background elements is one of the techniques that will play an important role in the finished portrait. This is composition. Don't make the mistake of believing you have to paint what you see in the background. Select those details that will complement your subject rather than detract. When photographing, position your subject to capture those complementary elements.
Bright light detracts from the subject in your portrait. When capturing a portrait outdoors, you have less control over the light. Use a canopied area, an umbrella or even a light reflection device placed to deflect sunlight from your subject. This will help give you a natural light source you can work with and one that won't detract from the details of your subject. This is particularly important for photography portraits.
The best outdoor photography takes place an hour before sunrise or an hour before sunset. These time slots are called the golden hours. Lighting is perfectly balanced for photography and can also be used when painting portraits. During these times, position your subject with the sun behind them for a balance of natural light that will bring out the highlights and contours of your subject
If your camera allows for portrait or landscape mode, choose to shoot in portrait mode when possible. Shooting in landsape makes it difficult to get close enough to your subject for a portrait without leaving empty places around the subject. Use the two-thirds rule when working with a portrait. Two-thirds of the visible area should be filled by your subject, with the rest of the visible area of the art devoted to background. The subject of the portrait should always be dominant.