Try it out a bit. It can be something as simple as recoloring some roofs, grass, and dirt:I find that HARD to do and often that just whip something up from pre-existing tiles is a lot easier...
Note: The trees and small rocks are from the free assets subsection of these forums (PandaMaru I believe was the artist who made them) the rest are just tiles I recolored and/or plants I copy/pasted out of their pots. Nothing too fancy, as I have minimal artistic talent when it comes to making anything from scratch.
And if you use custom assets from these forums, it can be as simple as clicking the right passability settings once you import them, and that's it. Give it a try, it's worth getting comfortable with.
Now THAT is a work of art!@Aesica What was that? Use Theme 6? Here's a cover version just for you. Enjoy.