Table of contents
Use HDRIs!
HDRIs or Spherical Images, how they got called, are images that get wrapped around a 3D scene to light the Scene. The benefit of using HDRI lighting is, that it brings a lot of details with it which is the reason, it makes the render much more realistic and on top of that, it is quick and easy to set up.
You can also supplement the HDRI lightning with some additional Lights if you want to brighten up a specific are a for example.
Since HDRI means High Dynamic Range Image, images with a higher Dynamic Range should be used, this can make a huge difference even if you don’t export your images in a High Dynamic Range.
You can recognize images with a high dynamic Range by their format. Formats like Radiance HDR, OpenEXR, TIFF and some other formats can contain HDR Images while Formats like JPEG or PNG can not.
To everyone who wants to create Studio light, I recommend the Blender Studio Light Add-on. It is a free Add-on that allows you, to create your HDRIs within Blender by using images of real Lamps which, like normal HDRIs also give you the advantage of the extra detail to create more realistic Renderings.
Bokeh
By using the Depth of Field feature which you can find in the Camera Menu you can create Bokeh which not only makes your Image more realistic since it emulates something which is happening inside a real Camera.
It also gives you the possibility, to hide things you don’t want to show, like parts with fewer details or seams in the texture. Because let’s face it, you can’t create everything with high details because it would take waaaay too long.
Another benefit of using depth of field is that it enables you to guide the viewer’s eye to a specific place.

Bevels
If you take a look around you, You won’t see many objects with sharp edges. There are some exceptions, like sharp or really thin objects. But these are just exceptions. And making something look realistic means making it look like it would in reality.
Also, If you create some more abstract motion graphics, this small light Edge can enhance the final result.
Motion Blur

Motion Blur is in every Photo or Video, sometimes it is so little that it is invisible or only gets recognized subconscious, but technically speaking it is there all the time. Which is the reason I recommend using it if realism is your goal.
To activate Motion Blur, you just have to tick the box that says Motion Blur, which you can find in the Render Settings.
Of course, you need to have a moving object in the Scene to see Motion Blur. If you have a still image, just animate the Camera a bit.
The default options should be right most of the time, but I still explain the settings to you.
Shutter
The Motion Blur is a build-up of two effects, the first one is called Shutter. Which in real life happens because the Camera captures the light through a small period of time. Usually the half-length of a Frame. This means if you’re filming with 24 Frames per second, the period of time in which the light hits the sensor is 1/48 second. With 25 Frames it is 1/50 second, with 30 frames it is 1/60 and so on.
The longer the time is the light can hit the sensor, the more Motion Blur you will get and vice versa. You can set the amount of time the light hits the sensor per Frame with the Shutter Option. Which is by default set to .5 which means how I mentioned the half-length of a Frame (24FPS 1/48s, 25FPS 1/50s, 30FPS 1/60s…) Which is the setting most cameras also have by default. You can also change this to 1 for Example which would mean the Light would hit the sensor the complete Length of the Frame which means 24FPS 1/24s, 25FPS 1/25s, 30FPS 1/30s…
You can use this if you want to combine Video and CGI and you had another Setting for the Shutter in your camera, but most of the time 0.5 will give you the most aesthetically pleasing results.

Rolling Shutter
The other Effect is The Rolling Shutter. The reason, that this happens in real life, is that the camera captures the Images in Lines from Top to Bottom. This happens quickly but not at the same time, which is the reason you can see it when it comes to fast-moving objects like cars or planes. It also happens with fast camera swivels.
In Blender, you can activate it by selecting Top-Bottom for The Rolling Shutter, which is currently the only option. You can set the strength with the Rolling Shutter duration, but also here the default settings will do their job most of the time.
Also, if Rolling Shutter gives you more realism, you should ask yourself if you want to use it because it is less aesthetically appealing compared to the normal Shutter Effect.