Well the obvious answer would be sculpt feathers on the neck. Just add feathers around the neck like a triangular patch of feathers like some kind of feather mane.
Pin the head to the body and create a neck out of gs. leave some space on the back for the feathers and let it cure.
After it has cured add a thin layer of
GS and sculpt the feathers in. Just make some layered triangular shapes like a scale mail armor and use your hobby knife and gently create a line in the middle of each feather useing two pressed in cuts. Then cut a series of slightly angled lines from the center line outwards as the feather texture. And if you still think you can go further, rough up the edges of each feather some more to get a more natural looking texture.
Here is a nice tutorial with pictures:
http://www.bolterandchainsword.com/topic/110011-modelling-a-how-to-do-feathers-and-wings-tutorial/ As you never have done any
GS work it might be best if you make a few test runs maybe around a piece of sprue or a flat surface.