@bex
What works for me when iam airbrushing close to realism is not looking at a portret as a face but as shapes.
So for example a eye is a pulled out circle , with a small circle in it , with straight or curved lines, so if i airbrush those exact circles , lines and other shapes it wil become a eye.
It is easy to get lost in a portret because the human brain indentifies a face as a complete thing, so if the eyes are nice, your vieuw will make the entire face more awesome and errors will be hard to see.
Some other tips:
1.Try to turn around your entire picture and airbrush a portret upside down , this will help being more objective and focus more on the shapes instead of the beautifull face.
2.If u start with for example hair and the focus is fading away, get away from the hair and start with a eye, this way you can't get the airbush block because u start something new.
The advantage of this is when u go back from the eye to the hair u will see all more clearly.
3. If your portret doesnt look good remember that the next one will always look better.
4. Human eyes get tired when looking at a picture for a long time , remember to take a rest for the eyes for 15 min every hour orsome.
U will see new errors or new tricks suddenly because your eyes are fresh again.
5. It is a gift to analize your own work and be critical about it , if u can see your own mistakes means u learned and will do better next time.
I hope this helps !
greets Souldog Airbrush