When in need of an extra layer of depth, life, dynamic and maybe even realism in your renderings, photoshop is probably your best friend. It gives you the ability to add overlays (and backgrounds) of light leaks, floating dust particles, soft glows and so forth. Combine all these elements and get a rendering that is way more interesting to look at.
See for yourself in the pineapple rendering below. Slide left and right to show the rendering before/after photoshop.
P.S.: Apply with care. It is so easy to go overboard with this. I generally tone all effects down to something like 80% when done applying them.
The pineapple model is a 3D-scan from www.blankrepository.com. A site that I linked to a few month back in my occasionally curated newsletter of links to KeyShot related resources, models, textures and more.
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