Elderly

This week pay particular attention to the elderly when you're making notes of people you see in your writer's notebook

As an exercise, try listing least a dozen ways to suggest someone is very old. Then scroll down and see some others that you may want to note as you're observing.
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oversized nose and ears
amount of hair (many women's hair thins as they age too)
hair line
color of hair
wrinkles
condition/thinness of skin
age spots
shaky hands
slow pace
unsteady gait
quality of vision
sensible shoes
pants hiked up
skeletal
posture
interests
condition of hearing
posture
quality of voice
bird-like appetite
eccentric
attitude or outlook
where they are on Saturday night

Half of the above are mine and half from "Funny, you don't look 75" in What If?: Writing Exercises for Fiction Writers by Anne Bernays and Pamela Painter.

(There's also a revised edition in hard back of What if? but I haven't seen that one yet.)