The first map is bad. Not only is it way too straight and boxy for any natural waterway, but there are some serious height errors with the cliffs. In particular, the ledges on the cliffs (the symmetric ones) should have as many cliff tiles as there are straight up to look right. And the waterfall. The top body of water is assumedly supposed to be at the same level as the tall cliffs. How can the waterfall then fall four tiles and be at the same level as the ground, which is nine or ten tiles lower than the cliff? And then how can there be an additional four tile waterfall when the same level of grass is adjacent to both the upper and lower body of water?
Read Rule #1 and Rule #4 -
http://rmrk.net/index.php/topic,13769.0.htmlThe second map is fine, but it could use a little more randomness and a little more clutter. It's a bit too empty. Also, you have some weird wall errors in the upper right part. Some sections are missing, some of the walls aren't right, and a couple of the walls are too tall or extend below where the wall just curved.
The third map is also not great. Besides what Zylos has said about the roof windows, the wall windows are missing their top half. Also, what is with the tiny fenced section and the random barrels scattered everywhere. Nature is random, but humans aren't.
Sorry if I sound a little harsh, but you shouldn't be making tile errors. Anyway, just keep at the mapping stuff and you will eventually become a better mapper.