Hi there, welcome =)
Just a few pointers in addition to the good advice you already got:
-
check this awesome tuto if you haven't already.
- about palettes: yours are made up of independent 'color ramps'. You need to tweak them into organic, connected palettes, as explained
here.
- about shading: I'd remove all 'decorations' on the sprite (yellow marks, red eyes) and shade it the best you can according to a light source. You can then add those back afterwards, but at this point they'll just interfere with the more basic work.
Some peeps find it useful to shade in grayscale and apply color later; you might try that.
Can't wait to see where you're going with this =)
Edit: posted before seeing your last edit.
It's better, but not there yet. Think of the most basic dog shapes, get those right first, add detail later.
It's nowhere near easy, because it supposes you have a clear idea of dog shapes = dog anatomy! Use references, lots of them.
And yes, too many colors. Again, start simple, then add them one by one when you really need them.
Edit edit: your light source is not clearly defined. Could be nice for a diffuse light atmosphere, but you should start with basic sunlight, 45° in the upper left corner