Hello, great work you have there ^^
The only major issue I've noticed right away is perspective - all vanishing points are going all around the place and mismatch each other, and some are even inverted, I mean your far side objects looks bigger than they should for this camera angle, even for an isometric grid it's too much. I would recommend to cross-check all lines by ruler or with special VP finding scripts, programs or whatever you using for that.
As for colors, the histogram graph shows quite a big green shift, I mean I am not sure if yellow+green is the best main colors combination, unless you specially wanted this effect ofc, idk.
I had some free time (just a hour) and made some corrections for you, mostly perspective (placed the horizon line at about the chest), and then added some fog, reflections and colors stuff too, here look ^^
emm.. I think I made it look worse actually xD
Anyway, I hope this would help you to improve, and to get some new ideas too ^^
