Yea...I'm a beginner to this whole site and heck, even to pixeling like this :O. But I'm gonna keep trying lol.
we require all unecessary backgrounds be made trasparent. I'd reference some isometric buildins from the gallery, the shading isn't making much sense right now. it's often best to shade one plane (like the slender wall) a different shade than a neighboring plane (like the front of the house), sans all the noise and dithering (helps define the edge and separate the two distinct planes). And I'm not sure what's going inside the house. the roof is also steeper on one side than the other
remember that the WIP forum is a great place to learn, no better way to improve than to get comments and critique, a fresh pair of eyes.
there's a pixel art tutorial in the forum as well as well.