Ageing a young face is based on a simple principle. On an older person the skin, where there is little or no bone, is sunken. On a younger person these parts are darkened (shadowed), the skin will appear to be really sunken at that spot.
For ageing we use Crème Make-up Pure because this works out easily and has good fluidic properties. For shadowing a brown colour is used. With Santa, do not apply the lines too strongly.