On Flash, see if you can scale the torso decal print up just a little, and cut the decal out slightly better.
You should also try to make the line of his mask straight on the bottom, and try to make the eyes sharper, more distinct and less "wavy". The decal itself is great, and much better than I could ever do.
On Darkseid, could you brighten the sticker print some? It would match the blue body better, and then the black would stand out more. And for free-handing the face, that's nice.
The decals are better than I expected, a little cleaning up of the prints, faces and colors will yield some pretty good custom mini-figures. You may want to think about decals for the faces though, as you could get a sharper and clearer image, and more details that way.