When i got to around 50 or so villagers, i found it diffucult to keep track of who was supposed to be doing what, so i started color coding them, the farmers wear greens, the scientists wear blue, blacks, the builders wear reds. When they get elderly, even though they can still work, I ussually change thier clothes to set them apart as "elders", the women wear that pastel dress and the men wear the red tattered skirt.
It certainly helps when i can see at a glance who is where, and I don't change them until the are adults, so i know right where all the kiddies are.