About those city screenshots... oh, wow... This is the kind of stuff I tend to see that doesn't get a lot of critique, or even comments. Things that have tons of things that... aren't really wrong, but aren't special in any way, either. I bet you spent a lot of time on these, and that's good. I don't have the patience for large projects, myself, sadly... But there's a LOT that could be improved here. The first thing that strikes me is the colors. Way too saturated and bright and... Plastic-MSPainty, like. You could benefit from some desaturation, and exploring other tones and shades. Don't be afraid to stray waaay far from the original palette.
Then we have textures. Most of the things there does have a texture, but it looks like.. well, a texture. Not like an actual surface. You seem to have a liking for straight lines, and the spraypaint tool. The spraypaint isn't just about the roofs, it's on the blue awning, too, and on the sidewalks. The sidewalks sometimes might be an okay place to use it, but I don't get the awning thing at all. In general, try to avoid it. Not only is it obvious that you were lazy and used the spraycan, but it also never looks good. It will _always_ look like a spray-canned area instead of a real material. And the lines.. same thing, except... well, I don't understand why they had to be lines. Personally, when I look at that beige house, I think manchester. And when I look at the road, I think vinyl. I doubt that was intentional, but that's what it looks like due to those lines. Seems textures is something you might want to take a closer look at and practice. It's not that hard to find references. Just look at something and try to imagine how you could represent that with pixels. The rest is just about practice.
And then there's shading, and outlines. I... can't specify anything exactly, but it's impossible to find a lightsource (something that every picture needs), and some object just look like random boxes floating around because of the lack of shading and the harsh outlines. Most notable are the boxy things on top of the buildings.
And finally, I have to take the liberty to ask: What's up with that tree??