ok heres the thing...
for google sketch up this is pretty good...the thing is though i would stop right here.
Google sketch up is meant as a practice tool, not a professional one.
i'd suggest once you are what, 3 months into this switch up to using either autodesk products, blender, or zbrush cause you ain't gona get far in the industry with this if your aiming for that at all.
don't take this as an insult but i want to help you like many other sketch users that they shouldn't rely on this program for the entirety of an art form.
its great but stuff from sketch doesn't work as well in games and ect ect than other program would offer.
but then again you don't have to listen to me, just my point of view on it.
good job nonetheless!
l8s