Sag the chin so it complements the saggy cheeks you've got.
Increase the depth of the line from the nose to the mouth.
Drop the lower area of the eyebrows (or the top eyelids) slightly.
Slightly enlarge the end of the nose and make it drop a very small amount.

In the older version you look like you've flattened the cheeks under the eyes. What you need to do is keep them as the young version and then create bags under the eyes, kind of like taking the area immediately under the eye (but not the cheekbone) back a small amount to form a near crease. Then you can baggy that up a little.

The best advice though is to search the web for images of old people and see how areas of the face change with age.

Good start though
I did a similar thing with a model head I was experimenting with. If its any use you can see it here:
https://www.flash-fx.net/3D/gallery/ -> scroll down to the generic head mesh bit and compare the second and third thumbnails for differences (click to open them large). Also the 7th thumbnail along is a kind of cartoony old man.

Simon