Hi there~ I'm pretty inexperienced with pixels as well, but I think I can give you a bit of advice. :D

You already have a good sense of how clothes look when worn, probably because you're an artist. I'd just say that your lines are a little shaky, and the outlines a bit too dark. Particularly on the hoodie. And even though you think it's gross, I like what you have going on with the dress. I think the palette might be hurting it, since that particular one isn't very contrasty so most items that use it tend to look flat.