The first picture (it's human, but wearing a crow-like skull/feather costume) I'm pleased with, but I'm putting it up for critique... what else would push this into "completed work" territory? It started as B/W using low flow hard round brushes, with a layer at the end for a bit of color.
The second pic, though, was a quick work that seemed cool for a few seconds... but thoroughly bores me now. This also applies to the first: How do you make an image really stand out? Where do I take these?
The first image needs more work on shading, it looks flat. Just look at it's arms, they look like they were more carved in stone than anything else, don't just add a lot white in one line and black in another one. Thing in shapes like cilinders and spheres for the shading. Also do you know how does it's body look? where are the arms placed under the costume? Even if you are not showing that you need to think in it.
Images with high contrast or with shading of different colors can stand out well.
With the first you have used black and white; once you introduce colour, B&W should be avoided as it flattens the picture. On the second your darks are not dark enough and you’ve used white for the highlights. Think of highlights as either warm or cool, a very faint blue or green would snap the second picture just that bit more. You might want to pay attention to the anatomy of the arm above the elbow as I’ve never seen a bulge like that.