1. Use surface imperfections – If the objects in your renderings appear to be very clean or accurate, it will seem a little unrealistic.
So, it is necessary to include some surface imperfections to the materials in your model.
2. Bevel your edges –Any accurate 90 degree edge exists in the real world. While viewing some objects having sharp corners and magnifying closer, a curvature or smoothness to that corner will be visible.
In computer graphics, this straight lines and sharp edges prevail by default. In order to check this, beveling or rounding the corners of your objects are recommended when required.
3. Use ambient occlusion – Ambient Occlusion alias AO stands for a shading process that allows you to generate soft shadows in cracks and crevices in any 3D objects while indirect lighting is thrown out into the scene.
Ambient Occlusion can provide more depth and definition to the geometry as well as more realism into your scene.
To learn how these are applied to a scene, go through the following video tutorial.