The Tips in detail

 "Learn how the human eye actually »sees« the world."

The human eye has limitations in focusing and some special means of recognizing colors and especially light! Adding a video post depth of field is a must if you do wide area renderings that span several kilometers (miles). This will increase renderingtime an needs some testing for all individual scenes (the default settings almost never meet your needs) but it really adds realism to your scenes (refer to "Coast", "Hase", "Sat Dish" and "Starfighter").

Another point is that the human eye blurs radially from the center of focus in all directions (spherically). This is due to the fact that the eye has an area wherein it focusses to get a sharp image although objects near this focal area stay visible. Everything nearer to or farer away from as well next to or above or below the center of this focal area is blured with increasing intensity. The intensity of blur grows from the center towards the rim.

Normally the human eye has less problems with the near-focus than with the far-focus by means of recognizing details. The nearer the focal node is located to the eye, the less individual objects can be focused at a time. This is because the nearer the focussed object is located towards the eye, the smaller is the focussing region. Consequently you should add a "depth of fields"-VP if you do extreme closeup-renderings, too.

As usual: adding this kind of video-post to your rendering increases the time it will take to render the image or animation.