Hello Chezza, I do not have a tutorial, but I would suggest that you need to do very little to your models to add “age”. As a painter, I’ve discovered that a little goes a long way. Sculpt your faces in the usual manner, making the hair gray, if the couple has gray hair with just a hint of laugh lines at the outer corners of the eyes. That is really all that is needed to suggest age without over-doing it.
I made a pair of glasses for my John Lennon model using a fine gauge wire, wrapping it around a skewer to form the lense frames. Just takes a little twiddling. They do not look great, but they worked.
Sugar Sugar by SSmiley
