I think I messed up the nice texture settings in the chalk brush early on in the process without noticing it. However, I am still quite happy with the result.
I tried out the liquify filter and I think this is a cool technique. Furthermore, I duplicated the drawing layer and set the second to overlay. I reduced the opacity of the overlay layer. Then I added a layer mask an only added the overlay layer in the eyes area to boost the contrasts a little bit.
I would be glad about some critique and inputs.
