Accurately extracting models and their hair from a background is one of the most irritating and time-consuming tasks a digital imager can be faced with - trying to make a smooth and detailed selection can leave you thumping the desk in frustration.
Making selections with the Pen tool can occasionally give you an adequate result, but it is virtually impossible to capture all of the fine strands and flyaway hairs using this technique. Both the Magic Wand and the Magnetic Lasso selection tools are similarly ineffective, since most images do not have a universal selection tolerance that will enable you to wand out unwanted backdrops, and even if you do manage to walk the incredibly frustrating magnetic tightrope, the background will still be present in between hair strands, leaving you with annoying halos.