If you make a map, best is to give everything a function. This will make it look more realistic.
For example if you make a house, what kind of house is it. Is it a house where someone lives, add furniture, is it a shop, add shop items. If its a buyable house, then make it a reason why it is on that place (is it some vip island?). Same goes for the white stone walls, why are they around that place. And the fences, also there isn't really a reason why there would be a fence since there is nothing in it.
About the walls/grounds, best is to stick to a few types that match. And if you make the houses a bit smaller with different shape and maybe some architecture it can also make a better effect.
The nature is mostly a bit empty, you can use the light grass and add some bushes/small fir trees. Also its better to use a few types of trees that match on most parts of the nature. Like: 2700,2701,2702,2707,2708. This will make it look more natural.
Overall, it looks like you're quite new at mapping and mapping is mostly practise. So keep it up and you will get better
