Shnitzelkiller… you must be German…I used to do Coat of Arms…When I commented on your space scene I meant no harm. Sometimes Im brutially honest and have no right to be. So heres my space scene…I dont know…looks like some kind of retarded ball on a bad hair day with eyelashes.
Great space scene - kind of reminds of the stars wars droid that everyone likes.
The desk: It has nice modeling and the texturing is reasonable. What you need to focus on is the overall image and lighting qualities. In this case the whole image is mainly too saturated. See this thread for good examples of taking an image to the next level of realism http://forums.cgsociety.org/showthread.php?t=359226 (It is for 2d, but the same principles apply).
The girl: The shirt looks like it is just a colored vertex group. The hair needs a more shiny material. The skin could probably be less shiny, at least on the arms. A more complete render (background, lightning setup), it looks a little like a viewport grab.