Well for one, that hardly looks like an Island. And the mountains? I wouldn't call that raised ground "mountains".
First, you need to expand your island a bit, and make it more centred in other words, surrounded by water. Atm that black boundary is ruining it.
Second, mountains can't be just raised from the ground like that and look nice. You need to add some walk able parts. If you've ever went camping in your country, in a forest perhaps maybe you'll know that there is always a way to get around the trees an cliffs. Expand the mountains, add grass/dirt tile here and there, add walkable paths, trees, grass.
Third, you need sand around the water, rocks, palms and probably the Village summer grass, the bright thick one, you'll notice it.
Forth and final, living the terrain up a bit. Adding fishes, crabs, and some other animals you think of.
Hope it helped.
