So, yeah. Haven't worked on these in awhile, but I figured I should start again. Started making two new enemies, the fox-face, and the mole thing. The problem that I'm having with them, and to a lesser extent, the rest of my artwork, is that none of them look very...pixel-arty. They look more like random MS-Paint drawings to me, and a lot of them don't really seem to go well together, like they're ripped from different games or something:

...the mole guy isn't finished, which partly explains his MS-Paint look, but I cleaned him up as best I could, and he still looks terrible. The fox is "done," meaning I've cleaned him up as well as I know how, and he still doesn't seem to fit in, nor does he look very pixel-artish. The stone sprite, and the mud surrounding the water also look too plain to be considered pixel art to me, but I have no idea how to add detail to them. Tried adding moss and stuff to the rock for texture, but it all looked awful.
Basically, I'm looking for advice on how to make my sprites and tiles match each other better. Right now, they all look like they're from different sources to me. = \
Also looking for advice on how to make the mole and fox better. They both look pretty bad to me right now.
Also, did an animation of the chicken jumping, and starting working on the fox's snake-crawling animation. Is there any way to slow down .gif files? Right now, they're both way too fast. (Using Graphics Gale right now!)
Thanks!
Edit: Thought one of the main reasons my art might look bad is because I'm drawing everything too large...tried doing a lower-res version of the fox, and came up with this:

He seems really choppy to me now, though. Any obvious flaws?
Edit 2: Removed some...don't know what it's called...banding, staircasing, in the tail. Actually, I think I replaced the banding with staircasing, hahah. I don't know what to do with his forehead, though. Looks a little weird to me with that straight 45 degree angle, but if I try making it rounder when he's that small, it gets really jaggy looking. = \

Edit 3: Tried to make his face and tail rounder and less choppy looking with some internal AA:

Edit 4: Added colored outlines...

...And that's all I can do to clean him up.
So what do you guys think? Are my original sprites too big? How can I make this fox better? Why is my mole so awful looking?
My whole day is free tomorrow, so I'm looking forward to working on these sprites all day long. Please help, so I'm not just digging myself further into a bad pixel art hole for eight hours tomorrow!