Sun is my favorite thing for photographs. It adds dimension and life to an image. And nothing will showcase skin's healthy glow more than natural sunlight. When the sun is out, I will always always opt for lighting situation called backlighting.
Why
Light coming behind the subject is incredibly flattering. If you pay attention to how musicians are lit during concerts, light is usually coming behind them for an epic effect. This lighting setup also brings attention to the subject- where you want it!
When
It's easier to have light come from behind the subject when the sun needs to be lower in the sky. Therefore, the best time to take pictures is before sunset or after sunrise. I schedule all my senior and engagement sessions to start 2 hours before sunset (I opt for the evening option because waking up for sunrise is hard) for this reason.
But even when it's not sunrise/sunset, the sun is likely still not coming straight down. And I will backlight as much as possible.
How
Walk around the location and watch people's heads as you do. When you're browsing around, look in the direction of the sun (so the shadow of the person you're looking at is in your direction). If you see someone's hair light up, boom! You've found a great place for backlighting!
Looking at trees is another good indication of pretty light. If you see a trees that are not in the shade, you'll likely be near a great photography location. Trees also block enough light so the sun is not too harsh on your subject, but let through enough light to still flatter the subject! Additionally, golden light in trees photographs beautifully in backgrounds.
What
Once you've found flattering lighting, have your subject face their own shadow plus or minus 45 degrees. And shoot away! Once you've found great light, take advantage of it and take plenty of shots there! Don't feel pressure to move until you're ready. Great photos are made by great light, not great locations (although who doesn't love both?)
Remember how I said plus or minus 45 degrees? Sometimes you'll get too much sunlight hitting your camera lens causing haze or sun flares. A simple solution is to have your client just turn 45 degrees.
Your photo quality will be dependent on your ability to find good light while shooting. No amount of editing can save a poorly taken photo. As a photographer, your first job is to learn how to recognize and take advantage of flattering light!