A house+Grass using a couple of tiles. Not the best by any means, but some tips would be grand ^^.
1.) The roof: Add some tiles that show holes, or imperfections. Perfect tiles are hardly impressive to look at. Also, the lack of a dark, sparse color gives the impression of very little depth.
2.) The windows: Maybe someone wants a preveiw of what's inside?
3.) The door: Same with the windows, except maybe you want a closed door instead.
4. ) The dark blue: They used it in Final Fantasy for shadows, but I'm not sure it looks so great on the front of the house. Probably because the dark red clashes with it so violently.
5. ) The grass: ... is too shiny! Lower the saturation or contrast... or add some yellower hues.
I'm being really critical here (sorry), and some stuff I may have said could be wrong... though, maybe they could make it better? I don't know...