First sprite? Constructive crtiticism?

[sheepo]

Hello! I am 13 and I have just started to make custom sprites. I kinda want to make pokemon-looking sprites. This sprite took me all day. I drew it on paper, scanned it, traced it, filled it in and shaded it, but it still doesn't look that good to me. It just looks flat. How do I make it look 3d-ish and cartoony? Thanks! What do you think of it? is it good for a first sprite? p.s. it is a penguin. I made it in gimp.