Why not look at people? Take your time to study real stuff and duplicate it. It might be wise to work with traditional medias first before converting this into pixel art as you are simplifying in each step (real > traditional > pixel).

You might also want to take a look at how proportions on the body relate to each other. Something like this http://en.wikipedia.org/wiki/Vitruvian_man. I think there was another Wikipedia article that had it in head heights.

I say it looks pretty good so far but a few things I could point out.
- His left leg looks completely snapped, well more so his ankle than anything. Looks as though his foot should point a lot more to our left.
- The way he's holding his "knife" looks a bit light and weak. Also why did you loose the cool semi-original arm wrap idea you had going on?
- I sort of liked how you had the belt shaded on our right in the second last version but you lost that when you added the "studs"?
- Jacket is a little dark for my tastes and I think Helm's version brought the right amount of brightness.
- Maybe his hair could use some highlights? Seeing as hair is usually shiny and has some spectral qualities.

I think my favorite so far is either the first one you did or the second one. First one seems to have the most dynamic and thought out lighting and the second one has the nicest colors.

What I think the pieces are lacking is lighting. Could just be me but it seems they are getting equal light on all parts of their bodies. It just isn't reading well.

I made a quick edit to give you an idea of how you could maybe add a bit more interest to them with some simple lighting.


Also the anatomy on the big guy seems a bit flaky.  Seems a bit stubby and thick. Not sure maybe someone can do a more in depth anatomy critique.

Looking good so far

Well first off this isn't pixel art so I'm not sure why it is posted in the Pixel Art section. Put it in the General Discussion section if you're going to put it anywhere.

Secondly I'm not sure there's a point in someone reusing other people's palettes unless it's for a challenge or working with hardware limitations and modes.

Thirdly if you are using other people's palettes would it hurt you to ask them?

Do you usually AA items/characters that can be against multiple backgrounds?

Yes and no. You would AA the interior of the sprite and could try some "selout" which a lot of people don't seem to like or maybe some light affected outlines that get lighter near the lightsource.

I was trying to imitate a style choice by using the thick lines and blocks of color on the pyramids.

If you want to do the thick outline approach similar to that of Yoshi's Island or whatever it might be best to give everything that outline (at least all the background and level elements) to keep more of a consistent style.

I'm not totally sure what parts need better buffering.  I've never used the terms "color ramps" and "buffering" (I really need to extend my vocabulary)  Are you saying that I need to have some kind of small gradient where I have shadows to make the transition smoother?

Basically the way I see it, any large color plane/block needs some sort of AA between it and the next color except in the circumstance that the colors are very close together and would not benefit from AA (or a buffer shade).

I made a little example of "color ramp" and "buffer shade" for you. In simplicity your color ramp would be, for example, all your greens from light to dark (or dark to light). Buffer shade would just be the shade that is in between two other shades.