Work left:1.Some crafts that fly in front and behind the building you see.
2.Greeble a city with low polygons.
3.Tall buildings at the back scene(paint or build models)
4.sea surface and atmosphere.
I can't say this image I submited is properly rendered(1200*900),but I still hope you could give your precious advice that I badly needed after it is limited to 550*410

bytheway,dose any one know how to get a bigger pic on this site?