Yeah it’s in the wrong forum. This should be in the traditional section.
As far as the image goes, Well first of all the stance is a bit unattractive. It just stands there, boringly upfront. The second thing is the environment, There’s too much black in this image.
As N30N mentioned, the perspective is wrong, so you’ll really need to learn how to draw it in there. Too me te last thing that would dramatically change this image is the camera viewpoint. If I as much hear a “Mech” being mentioned, I expect it to be huge. The best way to make something look huge is by using the frog perspective. Which will immediately increase drama in the image.
These are just a few pointers, stuff like this really enhances drawings. Just being aware of those things will give you an edge in drawing straight away.
PS: might want to check out MyPaint if you are going to do drawing/sketches. I prefer it much over GIMP when it comes to drawing.