Nice! Another tileset spriter ^^
Hm, not very bad for your first attempt. In general your sprites only lack shading, where outlines are pretty good. Now, I know it's a paint in the a** but sprites just won't look nice if you don't shade them. Also, Дон Пач said a lot off useful hints, I'll probably repeat some of the things he said.
I'll try to help out a bit:
[1st sprite]: Ok, what you should do is widen the roof a bit. Also, you should know that roofs in Pokemon games make shadows, so sprite a bit of shade under roofs. Because the building is "bending", all the parts that are further from our sight should be a bit darker. Also, if you're going with the windows of that size, they should bend with the house.
[2nd sprite]: You made a nice outline. But grass isn't perfect, and yours looks mirrored, sorry. You should also shade it. Give it circular shades, where the lightest tone should be at the top.
[3rd sprite]: Same as the first sprite. The windows here look like they are a part of the roof, maybe lower them a bit. The pipes (sorry for the bad word) should also give out a shadow and the right side of the looks a bit strange, I suggest that you shorten it.
[4th sprite]: Best so far. Now, the farther part of the roof should be darker. Also, congrats on making the farther part of the roof smaller, you have good perception.
[5th sprite]: Basically the same as for sprite number 3.
[6th sprite]: Roof needs shading. Now, there are two ways to do this. The first way is to make the left part lighter and the right side darker. The other way is to make the top of the roof (both sides) the lightest, and slowly work down to the bottom of the roof, making it the darkest. If you're going with the second way use dithering. Also remember that the roof itself makes a shadow.
[7th sprite]: Same as 3 and 5.
Hope I helped a bit.
