Please don't take my advice offensively. I don't intend to offend you, everything I say is meant to help you.
I do a lot of photomanipulations (my digital artwork is not displayed on this site though, here I do retouch only) and I recommend shooting against a solid plain background that will contrast with the model (especially if you cut the model out using the channels method) This makes for a much easier extraction from the original file's background.
Also make sure there is not a whole lot of distractions in the image, because again you need to remove the model from the background, and too many elements will cause more time consuming and frustrating work. You will need to edit around different 'tones' and 'values' instead of one solid background color.
Although the pic you provided is a sample,your picture its self needs to have better quality if you want to achieve a good manipulation using the model (not just using her as a reference). The flash here is harsh creating strong shadows behind her legs and the lighting falling on her is flat. This could still be fixed in post, but it will be more time consuming and the final result will not be as high quality. A really well executed photo to start with will yield the best results in the end.
Try to make the model the main focus, instead of loosing her in a sea of background. You want her to take up as much as the frame as possible so you have more detail to work with. Its a whole lot easier to edit a larger version of the model then a tiny one. If there is a particular background you really want to use, shoot it separately. But keep in mind angles and perspective, and also that the lighting will match.
It is possible to shoot the model on location and edit that one image, but I personally feel you have more control when the background and model are separate.
anyway, I am sorry if this confuses or upsets you. I hope I was of some help.