>>1961875There's no rigid formula, "Feather N pixels"
Depends on the drawing. The important thing is to place image over a contrasting color background so you can see what you're doing.
I magicwanded the main areas, expanded 1 and feathered 1.
I could see that would wipe out some of the thinner hair strands so I restored those areas.
Now all those little nooks and crannies will have to be cleaned up manually.
Zoom in and erase with a tiny brush. If jaggies appear, set the eraser to partial transparency.
Remember, you have an UNDO so you can afford to experiment.
