Right, this is not meant to be discouraging, but on the most part, I think you can judge for yourself how good something is; you don't need to post _everything_ you draw up here. I'm hoping you're not. Bring us the best samples and we'll tell you where you're going wrong.
It's like music practice. If you've ever learnt any musical instrument, you'll know that you don't get your friends around to listen to your every practice; you practice at home, locked in your room or whatever, until you get something good. _Then_ is the time to showcase it to your friends. Similarly with your art stuff. Seriously 80% of the stuff I produce I would be ashamed to show you guys (not that that's why I draw, I draw because I like it). So I don't, I go back to the drawing board (literally) and try something else.
So... go practice, in your own time, and bring us the good stuff. This is not, i repeat _NOT_, meant to be discouraging you, and it's not that we don't want to see your stuff. It's just that we don't want to see every single thing you turn out.