I am uncertain of where to add the blush on a figure's face should it be below the cheek bones or on top. I'm more concerned with regular rosy cheeks than depicting someone who is tired or angry.
If you take a look at the following link, I think you can see a very good example of some blush.
It is the "Wolf French Voltigeur bust" painted by Guy Herrick and he did a wonderful job at it, this dude is blushing like a cherry :lol: :lol:
To avoid rose cheeks i use the mix that Luca Olivieri uses. He mix some red with black to look at red wine.
Then small amounts on the cheek (like Guy) and fade that out.
You may also add touches of blush to the bottoms of nostrils, under the tip of nose as well as the bottom of earlobes. You'll get a nice warm zone in the center of the face.
I "try" to do that. Phil Kessling and Luca O do the same... only much better. :lol:
Take a look at some of Luca's stuff...
I use a small dot of indian red oil color, just below the cheek bones. The dot should be the smallest possible. Then carefully with circle movements of the brush I spread it accordingly and blend it. It works for me.