First of all, there is no "make it realistic" button
You have to picture in your mind what result you want to get.
LW and Kray are biased render which means it approximates reality, light behaviour, surfaces. And what drives the result is... YOU!
So my best answer would be know better what you are aiming for. Gather reference images of sofas, metal, glass and try to reproduce.
Then you'll see that your questions will me more precise.
Making realistic is a wiiiiide subject...
To be constructive, first of all be sure that you never use 100% diffuse! never
Use more realistic colors for light (they are almost never pure white)
Use more texture, blurred reflection, bump, diffuse maps... well there is a lot to consider.
Your image looks really white. Stick to simple settings in Kray and focus on your light and surfaces.
Always remember fresnel, energy conservation, details
I hope it helps.