What I do is make sure each villager learns 4 skills (usually Farming, Research, Building, and Healing) as soon as they reach age 14. Then I leave them on their own, i.e. I don't check any of the boxes in their Detail. Some refuse to learn more than one skill, forget them.

When the trained ones get to around age 40 or 50 they will usually be Masters in one or two things. Then I direct them to the skills that are lagging.