Here is my latest tiling test:

and its accompanying tiles:

i rather like the shapes i managed to create, but i'm nto sure of the palette or how much detail should go into them
here's a previous mockup:

and my progress so far (the latest tileset was done in a nice editor as opposed to paint, which is useful for on the fly tesellation stuff)

i'm not sure wether i should tone down the texturing on the grass, use mroe shades, and how i should work with the dirt.
i doubt readability will be an issue on either tileset as i haven't started sprites yet.
For mood/tone
The game is a small brawler which will have bright colors and lots of action
think of it as a mix between bomberman and wizards (i just made this correlation and it's sadly very close)