As someone who does NPR all the time, I can say that the hardest thing is to develop your own style of work. You don't want your images to look like all you have done is a couple of tweaks to a render, but to have a special quality that is your own. My suggestions would be: 1) look at what other people are doing and find styles that you like 2) look at architectural photography to get a sense of lighting. The image you posted has some very dark areas, and also has a rather cold color palette. A photographer will use warm fill lighting in various places that are in shadow. I also don't depend too much on the render, but hand draw a lot of elements using Photoshop and a pen tablet.