sorry bout the very late reply, my computer kind of died on me so taken some time just to get up and running properly again =/
Humn, right now your tile sets are very basic. that's not a problem! its great for a starting set =D but as I understand, you want to go beyond that. so lets talk Pokémon! the older Pokémon games go by the same style as you. blank base (just one colour) but they also do this and this.
on the first one, you see "living" tiles, they are premade to have "stuff" in them, grass, windtrails in sand and so on. the second one is what you are doing, it has a basic plain tile with extra tiles you can randomly add yourself. the first one is more modern, the second one is more retro, both styles are still popular. i prefer the first style because i can have a lot "less" in it and still have a feel of it being alive. but both of them are open for you to add in more things like flowers, shrubbery, trees and so on. you just have to do it a lot more in the second style =P
not sure my "wall of text" is easy to understand right now xD