Tablet practice-Bat

is the skin tone that color on purpose? I might suggest something a little bit lighter because as is, makes him look less "batty' and more like he's just not well. I would suggest using a regular skin tone and then adding a tint of a tallow color but that's up to you. just my two cents. His hair and wings look good, as well as his clothes although I don't know what you're going for but if it's an overall bat look you might want to put him in black but if not then not.
the lines for his face and neck look a little sketchy and uneven and I can't tell if you just messed up the anatomy on his neck or if that's just more of the crooked lines. I would suggest smoothing your line-work up for a neater look.
Overall not bad just needs some touch up really.