J. Sketchbook

[Ananda]

I second Eduardo's comment. The problem with some of those is that something in the light is darker than something in the shadow or vice versa (example: the ground and the shadow side of the building in the second one). Try to make colour secondary to value, maybe painting with overlay and color layers over greyscale if you aren't doing that already.
Keep it up, it's already a very good start.