Please help me to light a scene correctly, or better, in the best way. My goal is to make it as realistic as possible.

Actually, I was thinking about global illumination, as I'm using this lighting method very often for indoor-scenes (lightspot on a white plane etc.).
Now as my new scene is outdoor (a person leaning against a house-wall in a bright environment, like the deserts), which lights should I use?
Should I use white planes with a spotlight, too?
Or should I use the light-settings from Howie Farkes' Maple Meadows, as I own it?
Or should I use these skydomes for Tim Payne's skies (never tried this)?
Or just the Carrara-realistic-sky presets?

Or what IS the best way to light an outdoor-scene as realistic as possible in Carrara?

I feel as if I'm stuck with this....

Thanks a lot for your help!!!

~Sassy~

The best easy way to get great outdoor light is to put an outdoor HDRI in the scene background (under the scene settings tab). If you then render with global illumination it is super. It is still very good even without the GI.
Usually you need to bump up the intensity of the major distant light of the scene, often to 120%.
This bright light shows up small flaws in the highlight shaders sometimes. Some characters' highlight & shininess have to be toned down.

Yes, I've used HDRI lights in the past and they are really easy to use.
But somehow I'm not satisfied.
Please let's take an example. The first promo-pic here, I'm more than sure that this one has been made in this Studio thingy. I really like this light! Which settings would be necessary to achieve this light in Carrara? Is that a HDRI-map?
I'm not working with Studio, so I don't have a clue how that scene has been setup.

This promo images look like a simple skydome white or gray: add a background color white and use Sky Light and Inidirect Light to render. To get better shadows you can add a simple spot light with a low value and soft shadows on.

 I'm pretty sure that light gray to white gradient was used in the background settings. I've done it myself a number of times.