>"The lighting appears inconsistant and at times pillowshaded (why for example does the tail appear to be lit from below the character?)"

Because the sprite is 3 years old.

>"The two lighter shades of green are too close together to be worthwhile. Similarly; the number of shades of grey is overkill for such a small sprite."

I learned better in the last two years.

>And the eyes; one being two pixels and the other being only one looks weird. If going for the chibi/anime kind of look; make both of them two pixels. If not...just remove the left one, it shouldn't be visible from this angle.

It's on the other side of his muzzle, partly.

See http://www.pixeljoint.com/pixelart/91881.htm for a slightly more current sprite (Only a year and a half old.)

Also, I don't have access to the secret underground pallet and knowledge from the Hidden Order of the Spriter like everyone else on this site seems to have. I'm 100% self taught.

Solid effort; but:

The lighting appears inconsistant and at times pillowshaded (why for example does the tail appear to be lit from below the character?)

The two lighter shades of green are too close together to be worthwhile. Similarly; the number of shades of grey is overkill for such a small sprite.

And the eyes; one being two pixels and the other being only one looks weird. If going for the chibi/anime kind of look; make both of them two pixels. If not...just remove the left one, it shouldn't be visible from this angle.

[Not trying to be negative; just CC.]