Here's what I have so far. I'm attempting to give the skeleton a crown as if it's a king of sorts.
Take a look at a real wither skeleton,then imagine it without the ribcage. Just take the design style of the head,and do it to the body. I have made a wither skeleton skin before.
Making skins like the wither skeleton is pretty hard because unlike zombies or something they do not take on the form of a human and switching a thing with three heads and an oddly shaped body into a human shape is pretty difficult! But what I would do is pick the parts out of the body that I like and kind of add them if you know what I mean then add the bits of the end of the wither skeleton and make those the legs but if this is your first skin I reccommend finding what other wither skeleton skins are already available and editing them maybe. But the skin already looks alright so you might be able to just pull it off and create your own! But do far have a notch!
Take a look at a real wither skeleton,then imagine it without the ribcage. Just take the design style of the head,and do it to the body. I have made a wither skeleton skin before.
If I've been helpful. Give an internet.