you can't make PNGs transparent.
And I know you CAN make PNGs transparent...
Sorry, what?
Frankly, I can't imagine why anyone would actually want to give you c&c, seeing as you tend to either ignore it, or worse, refute it, claiming you already know this. Yes, I CAN shade. Yes, I DO know how to do this. Yes, I DO know this. Yes, I CAN do this. Shortly after, you drop the thread, and start something else, occasionally not even showing anything before dropping it once again. Whatever critique is provided is ultimately wasted effort on the part of the people attempting to help. So yes, you /are/ being rather rude, and to people who are taking time out of their day in the hopeful assumption that you actually give a hoot.
As far as c&c goes:
Your lines and curves are messy, like you sketched them out without doing any cleanup. Your shading is all over the place, messy, lacking in contrast, and uses entirely too many colors for what you're achieving. I could go on, but it'll likely get ignored anyway.