There is a difference betweening being self-taught or self-educated, and self-certified. It's possible to know something well and thoroughly without a teacher, but since it's so easy for us to deceive ourselves, and so hard to recognize our own blind spots, it's often important and useful to be examined from a external point of view. How to gain recognition or certification, if it's necessary, will be a part, but only part, of things I intend to discuss here.
For my own purposes, I have the realm of knowledge divided into seven major divisions.
1) Physical and natural Science,
2) Personal studies (human body, psychology, geography)
3) Elementary social studies (geography, physical anthropology, social groups)
4) Culture (Ideas, arts, artifacts)
5) Institutions (Family, Education, Economics, Government, Religion)
6) Sociology/Anthropology (Communities and peoples)
There are various other schemes for division of knowledge, including for instance the Dewey Decimal System, Library of Congress cataloging system, and indeed the departmental organization of any college or university. The details don't matter: the subjects you choose for emphasis will influence your organization. The important thing is to have one, and not have subjects scattered helter-skelter.
Another link that may be useful in self-education is: