I'm going to have a still image inserted within my film. I don't want it to look like a still image, so I thought maybe adding grain would be a good idea. But when I add grain in After Effects, the grain just stays there, and does not move, which is not what I wanted. How do I make the grain move?
Use Match Grain instead of adding grain and use a clip from your footage as reference. This way you'll get the same type of grain like in your footage. You will need to tweak the controls of the effect to get the best results.