All seem very plain. Blend the renders, put more effects in the BGs, and add depth. I suggest looking at tuts. ^_^
when ever i do this tut http://www.easyupload.us/index.php?act=picture&id=80 it freezes half way in. >_<
to be honest, those are good without tuts, i started without tuts and i got no where, and im starting with tuts, and im getting a little somewhere, but im still behind the line of greatness or atleast good.