1st, its hard to read... what's the man holding? where is his head (it should show a little), is that a single tower lit on one side? or a double tower half on fire (i can tell, but its hard)

2nd, ask yourself, what's the meaning of my image. this may not be a normal question for an artist, but think of it this way. what mood are you trying to portray? did he set his castle on fire? and he's enjoying his work? or is it on fire, and he just happens to stumble upon the horrific sight, and then sit down in a compfy chair.

next, make your scene believeable. is the castle on a cliff? if not, then the hill is too steep, even with your guy in front of it. if so, then make it rocky to show the drop off. why do the paths go in different directions? do they go through the valley? is there a bridge? how are the two connected?

are there any trees in your universe? you don't even have to show them, you could just use some shadows from the far side of the path to show they're there. are there any clouds?

anything you add dosen't have to look amazing, we'll help you work it along.

next thing to do is to choose your colors. this is where the mood of the scene comes in. if its sad/ from the castle being burned down, maybe you want to make it rainy and dark. or of he's just having sum fun buring down a castle for pleasure, you can make them fun colors. right now your grass is a little too blue, and your sky is WAAAYYY saturated.

as for the texture of the grass and gravel, play around with it, use shapes, colors, and sizes to make it interesting. if you're not sure, post what you have again, and we'll go from there.

Hope i didn't forget anything, and Hope this helps!