Hey dude, nice stuff ! I really like your industrial designs and enviros ! i think your main weakness is drawing faces from mind ! i suggest studying from loomis, you'll easily find his ebooks on internet ! Also in term of colors, i find your value good, but your colors temperature are sometimes wrong . A color is warm ( saturated ) in light and cool ( desaturated ) in the shadows, but also if you have an orange or yellow light, adding just a bit of blue in the shadow would look better, in order to have a good color harmony, it's good to use the complementary colors, even if it's just slightly ! Keep up the good work and show us improvments !