BA (Hons) Computer Animation Arts,
1st picture is so stunning! I think to improve, add a slight variation of a different colour :)
Yeah, I was mostly just experimenting with the building shapes, I didn't want to spend too ages adding loads of colour (there is some orange in it, but because of how the gradient map works and how I drew the original black and white image it didn't show well). Once I'm more decided on my building shapes/compositions I'll start adding in more colours.