The Effect of Applying Grain Texturing to Layered Objects with Various Opacity Types using Adobe Illustrator
I enjoy using grain textures in Adobe Illustrator. It allows for a blending that make certain regions pop out more.
Use — Effect > Texture > Grain — to apply this sort of texturing.
From within that panel, the feature enables the adjustment of the intensity, contrast and grain type to alter how the grain changes the color (as seen below) of the various vector objects.