What's your target platform, RTS? Bricks have noticeable scale differences from face to face, and as GOBEE said, those stairs and handrails look wrong.
Made changes to the fire and added embers that fly off of it, put some bricks around the fire places, added liquid, eyeballs, and tentacles inside the cauldron.
I'd recommend just opening the first link on that first wiki page: https://polycount.com/discussion/177913/improving-readability-in-composition-01 Then start applying those ideas to your own images. You can do this very quickly if you scale the image way down to thumbnail size so it's low resolution and therefore quick to…