A terrific article by Hanniel Evan Yucoco on how to make a clean and decent selection on tricky photographs that involve super fine hair, fur, leaves, and any fibre like elements.
When using the standard selection tool or the masking process, you may able to accurately select smooth edges.
We may use the colour range tool and the tweaking of levels and channels to select much difficult areas but that would also take too much time on manipulation and very complicated to follow.
The good news is that, PS5 or Photoshop CS5 has a tool called the QUICK SELECTION tool.
This tool also includes a very powerful sub tool called the REFINE EDGES tool, using the refine edges tool will greatly help and speed up editing tasks especially when you need to select out the hair or fur on subjects.
Fur further information see