Paintover
If you are making a still image, some painting in Photoshop can really contribute to a more detailed look. Don't forget to do it on separate layer(s). The idea is that you can reach it a lot faster by painting, than doing it in 3D. The downside is that it doesn't work with an animation or turntable (Fig.35).

Fig. 35
Fig.36 shows the model before the paintover and Fig.37 shows it after.
Chromatic Aberration
Chromatic aberration is an artefact that can be found in real world photography. In Photoshop there is a tool to get rid of that, but since we want to make our clean CG image look more "real”, we will use this tool to add chromatic aberration.
Basically what happens is that when red, blue and green light travels through a lens they will disperse in different directions and then hit the film of the camera in different places. Thanks to Robert Krupa and Gustav Tell at Milford Film and Animation who told me all about this artefact.
Combine visual layers: Add a new layer and combine all the visible layers on to it (Ctrl + Shift + Alt + E).
Add chromatic aberration: Choose Filter > Lens Correction. It's a really subtle effect, but I think it adds to the overall look in a good way (Fig.38 – 39).

Fig. 38

Fig. 39
Fig.40 – 41 show the before and after shots.