Trying to make a better design

After receiving some comments about the game graphics (teachers, friends...) I passed a month reading pixel-art tutorials... but I got nothing. I tried to make the game look better changing the brick block, adding different colours and grass, so I could randomly insert this one among the others to make it look more varied. Then I tried a stone block instead of a brick one, but I didn't like it. I want to make brick-blocks because... I loved Prince of Persia as a child and I wanted these walls to be like the ones in PoP (I know they don't now :P)