I enjoy using our backyard as a background. First of all I don't have to light everything and we love the trees.
For this photo I wanted to connect our daughter playing her viola to the outdoors.
I am shooting in TTL mode and after I take a shot I am using the compensation dials on the camera and the PocketWizard AC3 to adjust my exposure.
In the first photo I have the camera at -1 compensation and the flash on her face at 0 Compensation and the hair light at +2 compensation.
You really just have to play with this to get the results you want.
The idea with the two hot shoe flashes was to use them to compliment the lighting outside. I used one light to help separate the viola player from the background by putting the flash up high and using it as a hair light would be used in the studio. I am using the other flash as the main light and using the natural light to control the background.
Because I am outside I am using the PocketWizard radio remote system to be sure the signal is reaching the flashes.
Once you master the use of the one off camera hot shoe flash and you are ready to expand try this exercise yourself. See what results you come up with using your camera and flashes.