If anything, bringing your palette together a bit could make this a lot better instantly. Right now you've picked every object's 'natural' colour. What i mean by that (and i'm sure there's a generally accepted term for it that i'm not aware of) is that your bricks are orange, your sky is blue, your tank is brown and err.. i love you? (i'm sorry)
None of these things are affected by things like atmospheric hazing (also called atmospheric perspective, i believe), colour-tinting from the sun/sky, light reflecting off of one coloured surface onto another...
Take for instance the church off into the background: The roof is bright blue! Worse still, the house next to it has cyan windows, which would suggest there being a very, very bright light inside, especially considering how light it is outside.
It's commendable that you're taking the criticism to heart like you are, and that you're still working on this!