In addition to the basic features of each type of material, there are a bunch of tricks you can use to successfully mimic real world materials at ease. We will focus on the basics of these special features to get better and more realistic materials in an easy way.
In the real world, there will be lots of materials that show some roughness. In fact, most of the real world materials have that bumpiness in some degree. Only very flat surfaces such as mirrors will not show bumps at all. There is a way to get this effect inside modo without generating a dense geometry.
In the previous screenshot, you can see how bump mapping can affect the look of a material. The two cubes are assigned to the same material, but the one on the right has a bump map effect attached, showing the roughness that makes it more realistic and better looking. The one on the left is only a cube with a rust texture and looks polished because there is no bump mapping at all.