Last night, the following is one of the topic came up during me & David Balndy's manga workshop.
"How to draw 35 year-old character?"
One of the pupils Dominic told us that the colour contrast of the face would be one of the key elements of aging look: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0057985
What I think was there should be 3 more elements (see the image for an example) :
1 - Rounder the cheek lines younger she looks
2 - Smaller nose, mouth & shoulders, but bigger eyes & ears for a baby-face effect
3 - Bonier the face older she looks
35 years-old is a tricky age to visualise well, the character should'nt look too young like teenager, but not too old!
I normally combine above method to control the look of character's age.