some things I wanted to point out:
1) as already mentioned: work on a gray background.
If you want to have more of a painterly approach and work from a photo reference to get your colors and values, or try to get a photograph with fitting colors and weather conditions, it can help a lot.
Another possibility would be to get a stylized piece of art, if you are after a certain style and aren't sure how to stylize colors.
For the edit I pasted a neutral 50% gray and for mine I used a realistic base overcast sky color.
2)
The big and important point:work on the shading of the big forms. Texturing is nice and especially if we start out, we try to overemphasize minor detail (bricks & textures) over major detail, like the big forms of the house.
The architecture of the house can be simplified down in a few primitive cubes and pyramids which cutted tops.
It's really important to indicate plane changes (like in the roof) with value changes.
For my edit I brightened up the roof where the plane gets an angle closer to the horizontal, this emphasizes that those planes are coming towards the viewer and add a sense of space.
3) also consider cast shadows to establish depth relationships between forms. I added cast shadows beneth the roof, to really emphasize depth there and give a clue how massive the roos is.
Actually if it'd be a realistic painting with overcast sky the shadow would be a lot more subtle, but I wanted to communicate the idea what's happening.
4) the lantern (?) is a sphere. It's a bad idea to draw everything stictly from the front and to leave out any perspective. If the lantern is a sphere and no disk, the lines are "wrapping" around it. The angle strongly depends on the horizon and size, but generally I'd suggest that you look up how the horizon is used in a perpectivical projection. Even if it's for a game, using some of these perspectivical effect can communicate towards the viewer a much better understanding of form.
