What makes an analog look feel believable?
The convincing part is rarely one dramatic effect. It is the way contrast, color separation, highlight roll-off, grain, and a small amount of fading agree with one another. If any one of them shouts, the photograph starts to look processed instead of photographed.
FilmFX begins with a restrained recipe and lets you pull the whole treatment back with one intensity control. Use the before-and-after line on skin, pale walls, and deep foliage; those areas reveal exaggerated color quickest.