I've been spending time lately on a couple of art forums that I've found to be quite supportive of aspiring artists (and even pros). They encourage beginners and will provide constructive criticism if asked for.
WetCanvas is a broad based forum that covers most artist media with separate groups for each type. Each discussion group has its own distinct personality based on its members and moderators. All appear to be quite supportive and give good, constructive criticism.
ScribbleTalk is a more narrow focus forum that is oriented around drawing (scribbling) media -- graphite, colored pencil, pastel, etc. I've found them to be quite supportive.
If you are interested in getting more out of your art, check them out