That's part of my problem at the moment; I'm trying to give the background some purpose (as well as make it a little less busy, right now I feel like it's too distracting).

Any ideas how I could optimize that?

I agree. My specialties in terms of art came from repeatedly sketching until I got the final result I wanted, and then spriting it up the way it came out on paper, with final tweaks. It can seriously help you get a better grasp of the basics. Because eventually (something else worth pointing out here), I was able to just jump into spriting without having to sketch it out on paper first, and although it still helps from time to time if I'm really stuck, that ability can be a great boon (and certainly reduce the amount of time you sink into this hobby).

Very beautiful and provocative. The shades are perfect, and your distinction between background and foreground, I think, it spot-on. Well done.

Decided to do something I've never done before; a mockup. I didn't stray too far out of my comfort zone, though, as I'm making a top-down retro-styled game using Arne's 16-color palette.

Here's the basic spritesheet thus far.



And here's a test with a background idea.



Any C&C would be appreciated muchly. I'll update it every now and then with more stuff. General mockup tips are also a necessity, since I'm not entirely sure of what I'm doing :/
Thanks!

Awesome. It's not a bad start on your part, but I zoomed in a bit and it looks like you're using the wrong colors. One of the main differences I see is the fact that the colors on the flat surface on the top of your rock are not bright enough, and the hilights on the ides of the rocks are TOO bright.

Hope that made some sense :/ Good luck!