After falling in love with the beautiful film grain obtained using Ilford Delta 3200 film, I decided I had better learn how to do it in Photoshop, or I would be at high risk of starting to mess with smelly chemicals.
My usual method of simulating film grain was simply to add Gaussian Noise to the image. This proved VERY unsatisfactory at reproducing the look and feel of the Ilford film. So I had to find another way. The problem was that the noise was too fine and too evenly distributed. I needed to create bigger grains, and have them selectively appear more in the darker areas.
Browsing through the options revealed that PS has an Artistic filter called (duh!) Film Grain *slaps forehead*. OK Let's try this out.
First you choose a nice closeup shot, taken at high ISO:
Then you convert to B&W using the LAB mode method:
Oops, Auto Levels overdid it. Adjust the curves a bit: