3 - you can follow a course covering the 9 types in depth. Usually, when you listen to your type description, you can't not recognise yourself.
In any case, once you know your type, you need to study it thoroughly in order to be able to use this knowledge for your inner growth. Again, a teacher who has mastered the
Enneagram for him/herself is far better than a book. My experience is that this knowledge becomes "alive" in you, when it is transmitted orally to you, through a "live" experience.