Well the constraints of 8x8 sprites mean you have to be creatively abstract, so its more forgiving. Also, put a black border around everything and it looks better haha!
I know that the black border comment might have just been something small to make your art look better, but it has made my art much much better. Thanks!
For me it was the other way around.. I started with black outlines and I was dissatisfied and then spent most of my time trying to learn be able to do without them. Although they seem great for pico so far.