Forming and following conscience
Conscience is the judgment of reason about the moral quality of a concrete act. It must be followed and also formed through truth, prayer, Scripture, teaching, and honest reflection. It is not identical to preference or social pressure. A sincere conscience can err, so humility, learning, and attention to people affected by our choices remain necessary.
Follow the sources
An original library introduction, with sources for further study. This is a starting point rather than a complete treatment or a finished formation lesson.