[mothered]

I like this sketch a lot. I do think a bit of length from top to bottom would help even out the shape.  This could be achieved with adding the bottom jaw.

In terms of what to do next, tidy up the shape and lines as is, then play with it. Maybe vector it or find a way to edit on different layers so you can try out various additions.

You could turn this into the back of a kind of morbid trading card, or a logo, or a t-shirt design.

Perfectly said.

You've given quite a few options and If the OP takes this under advisement, I believe the result will be a good one. Not that there's anything wrong with the current sketch, but more so It's still In It's Infancy.