Looking good so far..How will you do the water?
this just may be my opinion. But I totally think you should just leave it like that! It looks so fun. Like a 3d/stop motion. Just my opinion... the lighting is nice. How realistic are you going to get?
It could use ground cover like shrubs and grass, but the overall flow of the landscape looks great.
Nice composition! One thing you might want to consider is how to make the landscape look lush -you can re-use the tree leaf textures as bushes and shrubs for the ground. The terrain can look more natural if you use more than one grass texture. Make an alternate version (use different source), and overlay it in spots, just like the dirt overlay we discussed. Same idea. I suggest covering any abrupt edges with grass tufts, shrubs, and dirt patches.