Which is more befitting for a non-specialist: seeking religious knowledge or offering advice, and is one of them more befitting than his [regular] work?

Seeking knowledge and inviting to Allah are among the best deeds. Invitation [to Islam] cannot be achieved without knowledge and insight, so one must begin by acquiring sufficient Sharia knowledge for the purpose of Dawah (invitation). It is best to combine seeking knowledge and Dawah by allocating time for each. If a student of knowledge is not in need of work and has enough to sustain himself and those he supports, then there is no harm in leaving work and devoting himself to seeking knowledge or Dawah.