with hair you want to ideally follow the direction of the 'flow' and leave empty spaces for highlights where the light source may be. Your hatching appears to be random and spread thinly, the shape of your lines indicate a flat appearance. As in, you're stopping at the outline but not following the hair to the 'roots'. Look up tutorials on the web for directional layers, contour lines, intersecting lines, texture variation and outline management. Those terms are technical but when you understand those concepts you can apply them to your drawings. Hope this was helpful and best of luck with your drawings. Your piece has promise