UPDATE: i adjusted the default sub-tool settings menu so it's a bit easier to use, and so you can easily adjust the texture scale.
UPDATE ver 3: edited due to issues with TOS
i like having little lines when i give a character blush to add texture, so i made an airbrush tool that does it all in one step
UPDATE ver 3: edited due to issues with TOS
examples of use:

use the airbrush to dab on the character's cheeks, or wherever you want the blush

to make it darker, run the brush over the area a couple of times

add highlights using a soft eraser

this brush is monochrome only, so to add color you'll have to use clipping masks or lock the transparency of the blush layer.
Old version