If you asked me what my favorite light source was when I started in photography 15 years ago, I'd immediately say the sun. If you asked me today, with over a decade more experience, I'd still say the sun. It is very pleasing for skin tones, it's large and even, it's often available when you're outside, and it's free! It is almost perfect. Almost.
IT'S ALL ABOUT SHADE AND BOUNCE
So remember 30 seconds ago when you read that I love the sun? Well I do, but I rarely, if ever, use it directly. Especially for portraits. It falls under the theory of "too much of a good thing". It is often too harsh and the shadows it casts on the other side of the face are just not pleasant (and hard to get rid of in post-processing. So how do you get the best of the sun, without the negatives? Move into the shade. Not too far in, just a few feet. The shade of trees, a house, a building, whatever is around. In the photo world this is called open shade.
One of the biggest reasons to be in open shade is so you can use a bounce to fill in any shadows. That is because the bounce can be placed in the direct sun. In the photo above, we used a bounce card, held in direct sunlight just below and to the left of the subjects. This way all the lighting CAN be from the sun, just from different angles and diffused. It provides good balance to the lighting and a soft natural effect. I actually didn't use any fill flash for this shot.
Bounces can be purchased online in multiple sizes designs and colors. Bounces are typically white, silver and/or gold. There are reasons for this and you should search Google for the reasons why (I don't want to waste the time doing so here, but it is important to know - bouncing is the Holy Grail of photography lighting).
Though I own one, I also made a mini one for my Speedlite flash. In a big room with a tall ceiling, it is priceless. If you are interested, there are plenty of Youtube videos and Google posts that show you how to make ones of different shapes and sizes. If you want to play with the idea of using a bounce, buy a large piece of foam board from the craft store and go crazy.
One last tip for shooting in the sun: Never shoot mid-day. Shoot within the first two hours of sunrise or wait until late afternoon, within a few hours of sunset. The color cast of the light is warmer - more yellow/orange. It is great for skin tones. And never forget that some overcast days can offer good lighting too. No shadows to deal with! Try taking some portraits outside on sunny days, overcast days, early morning, mid-afternoon (eek!). See what you can learn from your own experience.