I haven't used oils in several years since I fully converted to Andrea/Vallejo acrylics.
Looks like you put too much oil on. See how it's kind of lumpy? There's an excellent feature here on using oils over acrylics.
I think the irises of the eyes need to be wider. They almost look reptilian. There should be a bit less white. Also, I can't tell, but you want to use an off white with a pinkish tone for the whites.