welcome to the matte painting forum here @ CG talk. well I think you have to follow some rules before doing a “final” matte painting, most of the new guys in this art are missing a lot of traditional skills in order to achieve a good looking image, I will try to explain what you need and what you are missing in this image
before anything get photo reference of the mood,architecture,lighting you will need.
then, always start with rough sketching, just to see how VISUAL composition will make your elements flow through the frame, and maybe with some colors already in mind (thanks to the reference material) you can start experimenting with color palette in your rough sketch
don’t forget to use always linear perspective !
these thing are the most important things before starting a final image!
I suggest that you visit the tutorial section here where we have some nice links to visual composition and other traditional skills you need
about this image, there’s no visual composition at all, you need something more interesting, balance, also the lighting is no helping, even though you have some very saturated red clouds there, the city is not.and I don’t see any light mood /intention
on images like this, dramatic mood is a must.look at some other similar matte paintings and see what you are missing, just bye staring hours at them you will learn a lot
you need aerial perspective for the city also*
hope this helps