what can i do to improve this image , more realistic, what lighting you will use?
thanks
How about starting with lowering your camera to eye level. That way you have the staircase as a scale.
Then you can start on materials and textures.
Marc
use a different sky image
I can’t tell but I don’t think you are using a HDRI. Try using one to light your scene.
I would start by moving the sun around so it lights more of the tank (I’m assuming that’s what the main element is). Place it somewhere on the upper right so the shadows are cast to the left of the image giving everything more contrast and depth. I also agree that the sky needs to be tweaked - definitely lighter, perhaps with some faint yellow at the horizon. Good luck!
were i can find more sky images?
i´m not using hdri image, i use direct ligth with vray sadows.
thanks with coments 
aLeZ.
My opinions:
Move the sun for more texture, but keep it on the left side.
Rotate the camera counter-clockwise (in reference to the ground) so we can see a little more of the second tank.
I like the camera level. We can see the scope of the project.
cool! I like it the way it is 
. Seems a bit “mystic” to me
I think when you apply a texture to the ground, it will help the image greatly. Way to much white in scene right now! I agree about the sky also.
Try just a simple gradient for the sky. Simple, but often very effective with an industrial image such as this.
Nice model so far, but supports under the piping would also help with the realism.
Tony