“….hair and posed, clothed figures”….

That sounds like you are referring to Poser renders.
If that is the case, the easiest thing to do is to save your Poser render as a Png file.
When opened in Photoshop the background will already be gone.

Or save the render to either a Tiff or PDS file, and you will have a perfect mask in the Alpha channel to use as your cutout selection.

 

SWAMP