First post!!

My trade is programming, but I have wanted to try my hand at pixel art for a while now. I have no art background or formal education in the area. Tried a few times last year, but I gave up. Anyway, my enthusiasm was recently reborn and I found this forum while searching for tutorials.
I need some well deserved critique on all the art I've "finished" so far. What have I done wrong, and more importantly what have I done right.
Messing around and trying to create a shield. Each row is a new try and I think I got it right on the 3rd for the small shield. I decided to try my hand at a larger version.

Little walking elf animation I did for fun:

Ship I did when I got into pixeling the first time:

Anyway, commence the critiquing, TAKE COVER!