Lots of actions will earn activity points in Narrative - creating content, voting (up-voting/down-voting content, voting for moderators, approving niches), commenting, tipping, etc.  And keep in mind that the rewards you earn will be influenced by your reputation. Thus, a low reputation user will not accumulate as many points/activity rewards as a higher reputation user.

Bottom line, though, the more that you contribute, be it posting content or providing feedback via votes, and other mechanisms, the more points you will earn and the larger share of the activity rewards pie you will receive.