I always like where possible to get things right in camera. The above shot was taken outside in the garden, the sun was a light source but I also used a Elinchrom flash head and large softbox on a C Stand, the flash was actually the main source and the daylight as fill, but often its just not possible to do this kind of thing as the location is not suitable.
It is in situations like this where compositing can be the answer. You take a photo outside to use as a background and take the main photo in the studio. You then combine the two using photoshop.
The key to making a realistic composite is making the lighting match and shooting with the intention of making a composite.
The above shot would make a likely composite. The plain background was due to a seamless infinity curve in the studio, would make it easy to select just the model and place it on a background.
For the backgrounds I have never had a lot of success but then I read some tips on Scott Kellby’s blog about shooting for backgrounds.
Check it out and have a go, I know I will.